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http://rosettacode.org/wiki/Execute_a_system_command | Execute a system command | Task
Run either the ls system command (dir on Windows), or the pause system command.
Related task
Get system command output
| #Clojure | Clojure | (.. Runtime getRuntime (exec "cmd /C dir")) |
http://rosettacode.org/wiki/Factorial | Factorial | Definitions
The factorial of 0 (zero) is defined as being 1 (unity).
The Factorial Function of a positive integer, n, is defined as the product of the sequence:
n, n-1, n-2, ... 1
Task
Write a function to return the factorial of a number.
Solutions can be iterative or recursive.
Support for trapping negative n errors is optional.
Related task
Primorial numbers
| #AntLang | AntLang | factorial:{1 */ 1+range[x]} /Call: factorial[1000] |
http://rosettacode.org/wiki/Exponentiation_operator | Exponentiation operator | Most programming languages have a built-in implementation of exponentiation.
Task
Re-implement integer exponentiation for both intint and floatint as both a procedure, and an operator (if your language supports operator definition).
If the language supports operator (or procedure) overloading, then an overloaded form should be provided for both intint and floatint variants.
Related tasks
Exponentiation order
arbitrary-precision integers (included)
Exponentiation with infix operators in (or operating on) the base
| #Icon_and_Unicon | Icon and Unicon | procedure main()
bases := [5,5.]
numbers := [0,2,2.,-1,3]
every write("expon(",b := !bases,", ",x := !numbers,")=",(expon(b,x) | "failed") \ 1)
end
procedure expon(base,power)
local op,res
base := numeric(base) | runerror(102,base)
power := power = integer(power) | runerr(101,power)
if power = 0 then return 1
else op := if power < 1 then
(base := real(base)) & "/" # force real base
else "*"
res := 1
every 1 to abs(power) do
res := op(res,base)
return res
end |
http://rosettacode.org/wiki/Extend_your_language | Extend your language | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
Some programming languages allow you to extend the language. While this can be done to a certain degree in most languages (e.g. by using macros), other languages go much further. Most notably in the Forth and Lisp families, programming per se is done by extending the language without any formal distinction between built-in and user-defined elements.
If your language supports it, show how to introduce a new flow control mechanism. A practical and useful example is a four-way branch:
Occasionally, code must be written that depends on two conditions, resulting in up to four branches (depending on whether both, only the first, only the second, or none of the conditions are "true"). In a C-like language this could look like the following:
if (condition1isTrue) {
if (condition2isTrue)
bothConditionsAreTrue();
else
firstConditionIsTrue();
}
else if (condition2isTrue)
secondConditionIsTrue();
else
noConditionIsTrue();
Besides being rather cluttered, the statement(s) for 'condition2isTrue' must be written down twice. If 'condition2isTrue' were a lengthy and involved expression, it would be quite unreadable, and the code generated by the compiler might be unnecessarily large.
This can be improved by introducing a new keyword if2. It is similar to if, but takes two conditional statements instead of one, and up to three 'else' statements. One proposal (in pseudo-C syntax) might be:
if2 (condition1isTrue) (condition2isTrue)
bothConditionsAreTrue();
else1
firstConditionIsTrue();
else2
secondConditionIsTrue();
else
noConditionIsTrue();
Pick the syntax which suits your language. The keywords 'else1' and 'else2' are just examples. The new conditional expression should look, nest and behave analogously to the language's built-in 'if' statement.
| #Nim | Nim | import macros
proc newIfElse(c, t, e: NimNode): NimNode {.compiletime.} =
result = newIfStmt((c, t))
result.add(newNimNode(nnkElse).add(e))
macro if2(x, y: bool; z: untyped): untyped =
var parts: array[4, NimNode]
for i in parts.low .. parts.high:
parts[i] = newNimNode(nnkDiscardStmt).add(NimNode(nil))
assert z.kind == nnkStmtList
assert z.len <= 4
for i in 0 ..< z.len:
assert z[i].kind == nnkCall
assert z[i].len == 2
var j = 0
case $z[i][0]
of "then": j = 0
of "else1": j = 1
of "else2": j = 2
of "else3": j = 3
else: assert false
parts[j] = z[i][1].last
result = newIfElse(x,
newIfElse(y, parts[0], parts[1]),
newIfElse(y, parts[2], parts[3]))
if2 2 > 1, 3 < 2:
then:
echo "1"
else1:
echo "2"
else2:
echo "3"
else3:
echo "4"
# Missing cases are supported:
if2 2 > 1, 3 < 2:
then:
echo "1"
else2:
echo "3"
else3:
echo "4"
# Order can be swapped:
if2 2 > 1, 3 < 2:
then:
echo "1"
else2:
echo "3"
else1:
echo "2"
else3:
echo "4" |
http://rosettacode.org/wiki/Extend_your_language | Extend your language | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
Some programming languages allow you to extend the language. While this can be done to a certain degree in most languages (e.g. by using macros), other languages go much further. Most notably in the Forth and Lisp families, programming per se is done by extending the language without any formal distinction between built-in and user-defined elements.
If your language supports it, show how to introduce a new flow control mechanism. A practical and useful example is a four-way branch:
Occasionally, code must be written that depends on two conditions, resulting in up to four branches (depending on whether both, only the first, only the second, or none of the conditions are "true"). In a C-like language this could look like the following:
if (condition1isTrue) {
if (condition2isTrue)
bothConditionsAreTrue();
else
firstConditionIsTrue();
}
else if (condition2isTrue)
secondConditionIsTrue();
else
noConditionIsTrue();
Besides being rather cluttered, the statement(s) for 'condition2isTrue' must be written down twice. If 'condition2isTrue' were a lengthy and involved expression, it would be quite unreadable, and the code generated by the compiler might be unnecessarily large.
This can be improved by introducing a new keyword if2. It is similar to if, but takes two conditional statements instead of one, and up to three 'else' statements. One proposal (in pseudo-C syntax) might be:
if2 (condition1isTrue) (condition2isTrue)
bothConditionsAreTrue();
else1
firstConditionIsTrue();
else2
secondConditionIsTrue();
else
noConditionIsTrue();
Pick the syntax which suits your language. The keywords 'else1' and 'else2' are just examples. The new conditional expression should look, nest and behave analogously to the language's built-in 'if' statement.
| #OCaml | OCaml | (* Languages with pattern matching ALREADY HAVE THIS! *)
let myfunc pred1 pred2 =
match (pred1, pred2) with
| (true, true) -> print_endline ("(true, true)");
| (true, false) -> print_endline ("(true, false)");
| (false, true) -> print_endline ("(false, true)");
| (false, false) -> print_endline ("(false, false)");;
myfunc true true;;
myfunc true false;;
myfunc false true;;
myfunc false false;; |
http://rosettacode.org/wiki/FizzBuzz | FizzBuzz | Task
Write a program that prints the integers from 1 to 100 (inclusive).
But:
for multiples of three, print Fizz (instead of the number)
for multiples of five, print Buzz (instead of the number)
for multiples of both three and five, print FizzBuzz (instead of the number)
The FizzBuzz problem was presented as the lowest level of comprehension required to illustrate adequacy.
Also see
(a blog) dont-overthink-fizzbuzz
(a blog) fizzbuzz-the-programmers-stairway-to-heaven
| #Ruby | Ruby | 1.upto(100) do |n|
print "Fizz" if a = (n % 3).zero?
print "Buzz" if b = (n % 5).zero?
print n unless (a || b)
puts
end |
http://rosettacode.org/wiki/Extensible_prime_generator | Extensible prime generator | Task
Write a generator of prime numbers, in order, that will automatically adjust to accommodate the generation of any reasonably high prime.
The routine should demonstrably rely on either:
Being based on an open-ended counter set to count without upper limit other than system or programming language limits. In this case, explain where this counter is in the code.
Being based on a limit that is extended automatically. In this case, choose a small limit that ensures the limit will be passed when generating some of the values to be asked for below.
If other methods of creating an extensible prime generator are used, the algorithm's means of extensibility/lack of limits should be stated.
The routine should be used to:
Show the first twenty primes.
Show the primes between 100 and 150.
Show the number of primes between 7,700 and 8,000.
Show the 10,000th prime.
Show output on this page.
Note: You may reference code already on this site if it is written to be imported/included, then only the code necessary for import and the performance of this task need be shown. (It is also important to leave a forward link on the referenced tasks entry so that later editors know that the code is used for multiple tasks).
Note 2: If a languages in-built prime generator is extensible or is guaranteed to generate primes up to a system limit, (231 or memory overflow for example), then this may be used as long as an explanation of the limits of the prime generator is also given. (Which may include a link to/excerpt from, language documentation).
Note 3:The task is written so it may be useful in solving the task Emirp primes as well as others (depending on its efficiency).
Reference
Prime Numbers. Website with large count of primes.
| #Pascal | Pascal | http://www.primos.mat.br/Ate100G.html ->
75. de 16639648367 a 16875026921
76. de 16875026963 a 17110593779
77. de 17110593791 a 17346308407
...
my unit:
750000000 16875026921
760000000 17110593779
770000000 17346251243 <----Wrong
|
http://rosettacode.org/wiki/Execute_Brain**** | Execute Brain**** | Execute Brain**** is an implementation of Brainf***.
Other implementations of Brainf***.
RCBF is a set of Brainf*** compilers and interpreters written for Rosetta Code in a variety of languages.
Below are links to each of the versions of RCBF.
An implementation need only properly implement the following instructions:
Command
Description
>
Move the pointer to the right
<
Move the pointer to the left
+
Increment the memory cell under the pointer
-
Decrement the memory cell under the pointer
.
Output the character signified by the cell at the pointer
,
Input a character and store it in the cell at the pointer
[
Jump past the matching ] if the cell under the pointer is 0
]
Jump back to the matching [ if the cell under the pointer is nonzero
Any cell size is allowed, EOF (End-O-File) support is optional, as is whether you have bounded or unbounded memory.
| #AppleScript | AppleScript |
set codeString to text returned of (display dialog "Enter BF code:" buttons "OK" default answer "")
set inputString to text returned of (display dialog "Enter input string" buttons "OK" default answer "")
set codePointer to 1
set loopPosns to {}
set tape to {}
set tapePointer to 1
set output to {}
set inputPointer to 1
set step to 0
set thePath to (path to desktop as Unicode text) & "log.txt"
set debug to (open for access file thePath with write permission)
write (step as string) & " (" & ((codePointer - 1) as string) & "): (The program contains " & ((length of codeString) as string) & " instructions.)
" to debug
set step to 1
on betterMod(x, y) -- so -2 mod 256 is 254 instead of -2
local x
local y
try
return -y * (round (x / y) rounding down) + x
on error eMsg number eNum
error "Can't call betterMod() on " & eMsg number eNum
end try
end betterMod
repeat while codePointer ≤ length of codeString
set theChar to (get character codePointer of codeString)
if (theChar = "+") then
repeat while (length of tape < tapePointer)
set tape to tape & 0
end repeat
set item tapePointer of tape to betterMod(((get item tapePointer of tape) + 1), 256)
write (step as string) & " (" & ((codePointer - 1) as string) & "): " & (item codePointer of codeString) & " | a[" & ((tapePointer - 1) as string) & "]= " & ((item tapePointer of tape) as string) & "
" to debug
else if (theChar = "-") then
repeat while (length of tape < tapePointer)
set tape to tape & 0
end repeat
set item tapePointer of tape to betterMod(((get item tapePointer of tape) - 1), 256)
write (step as string) & " (" & ((codePointer - 1) as string) & "): " & (item codePointer of codeString) & " | a[" & ((tapePointer - 1) as string) & "]= " & ((item tapePointer of tape) as string) & "
" to debug
else if (theChar = "<") then
set tapePointer to tapePointer - 1
write (step as string) & " (" & ((codePointer - 1) as string) & "): " & (item codePointer of codeString) & " | array pos. now " & ((tapePointer - 1) as string) & "
" to debug
else if (theChar = ">") then
set tapePointer to tapePointer + 1
write (step as string) & " (" & ((codePointer - 1) as string) & "): " & (item codePointer of codeString) & " | array pos. now " & ((tapePointer - 1) as string) & "
" to debug
else if (theChar = "[") then
repeat while (length of tape < tapePointer)
set tape to tape & 0
end repeat
write (step as string) & " (" & ((codePointer - 1) as string) & "): " & (item codePointer of codeString) & " | Array[" & ((tapePointer - 1) as string) & "] is '" & ((item tapePointer of tape) as string) & "'" to debug
if (item tapePointer of tape ≠ 0) then
set loopPosns to loopPosns & codePointer
write " ** Loop nesting level: " & (((length of loopPosns) - 1) as string) & ".
" to debug
else
write "
" & (step as string) & " (" & ((codePointer - 1) as string) & "): " & (item codePointer of codeString) & " | Not entering a loop but skipping to instruction number " to debug
set matchLoops to 1
repeat while matchLoops ≠ 0
set codePointer to codePointer + 1
if (item codePointer of codeString = "[") then
set matchLoops to matchLoops + 1
else if (item codePointer of codeString = "]") then
set matchLoops to matchLoops - 1
end if
end repeat
write ((codePointer - 1) as string) & "
" to debug
end if
else if (theChar = "]") then
repeat while (length of tape < tapePointer)
set tape to tape & 0
end repeat
write (step as string) & " (" & ((codePointer - 1) as string) & "): " & (item codePointer of codeString) & " | Array[" & ((tapePointer - 1) as string) & "] is '" & ((item tapePointer of tape) as string) & "'
" to debug
if (item tapePointer of tape ≠ 0) then
write (step as string) & " (" & ((codePointer - 1) as string) & "): " & (item codePointer of codeString) & " | looping back to " & (((item (length of loopPosns) of loopPosns) - 1) as string) & "
" to debug
set codePointer to (item (length of loopPosns) of loopPosns) - 1
end if
if (length of loopPosns > 1) then
set loopPosns to items 1 thru ((length of loopPosns) - 1) of loopPosns
else
set loopPosns to {}
end if
else if (theChar = ".") then
repeat while (length of tape < tapePointer)
set tape to tape & 0
end repeat
write (step as string) & " (" & ((codePointer - 1) as string) & "): " & (item codePointer of codeString) & " | output '" & ((item tapePointer of tape) as string) & "' " & string id (item tapePointer of tape) & "
" to debug
set output to output & item tapePointer of tape
else if (theChar = ",") then
repeat while (length of tape < tapePointer)
set tape to tape & 0
end repeat
if (inputPointer > length of inputString) then
set inputPointer to 1
end if
set item tapePointer of tape to id of item inputPointer of inputString
set inputPointer to inputPointer + 1
write (step as string) & " (" & ((codePointer - 1) as string) & "): " & (item codePointer of codeString) & " | read in " & string id (item tapePointer of tape) & " (" & ((item tapePointer of tape) as string) & ")
" to debug
end if
set codePointer to codePointer + 1
set step to step + 1
end repeat
set strout to string id output
display dialog strout
close access debug
|
http://rosettacode.org/wiki/Evolutionary_algorithm | Evolutionary algorithm | Starting with:
The target string: "METHINKS IT IS LIKE A WEASEL".
An array of random characters chosen from the set of upper-case letters together with the space, and of the same length as the target string. (Call it the parent).
A fitness function that computes the ‘closeness’ of its argument to the target string.
A mutate function that given a string and a mutation rate returns a copy of the string, with some characters probably mutated.
While the parent is not yet the target:
copy the parent C times, each time allowing some random probability that another character might be substituted using mutate.
Assess the fitness of the parent and all the copies to the target and make the most fit string the new parent, discarding the others.
repeat until the parent converges, (hopefully), to the target.
See also
Wikipedia entry: Weasel algorithm.
Wikipedia entry: Evolutionary algorithm.
Note: to aid comparison, try and ensure the variables and functions mentioned in the task description appear in solutions
A cursory examination of a few of the solutions reveals that the instructions have not been followed rigorously in some solutions. Specifically,
While the parent is not yet the target:
copy the parent C times, each time allowing some random probability that another character might be substituted using mutate.
Note that some of the the solutions given retain characters in the mutated string that are correct in the target string. However, the instruction above does not state to retain any of the characters while performing the mutation. Although some may believe to do so is implied from the use of "converges"
(:* repeat until the parent converges, (hopefully), to the target.
Strictly speaking, the new parent should be selected from the new pool of mutations, and then the new parent used to generate the next set of mutations with parent characters getting retained only by not being mutated. It then becomes possible that the new set of mutations has no member that is fitter than the parent!
As illustration of this error, the code for 8th has the following remark.
Create a new string based on the TOS, changing randomly any characters which
don't already match the target:
NOTE: this has been changed, the 8th version is completely random now
Clearly, this algo will be applying the mutation function only to the parent characters that don't match to the target characters!
To ensure that the new parent is never less fit than the prior parent, both the parent and all of the latest mutations are subjected to the fitness test to select the next parent.
| #APL | APL | evolve←{
⍺←0.1
target←'METHINKS IT IS LIKE A WEASEL'
charset←27↑⎕A
fitness←{target+.=⍵}
mutate←⍺∘{
(⍺>?(⍴target)/0){
⍺:(?⍴charset)⊃charset
⍵
}¨⍵
}
⍵{
target≡⎕←⍵:⍵
next←mutate¨⍺/⊂⍵
⍺∇(⊃⍒fitness¨next)⊃next
}charset[?(⍴target)/⍴charset]
}
|
http://rosettacode.org/wiki/Fibonacci_sequence | Fibonacci sequence | The Fibonacci sequence is a sequence Fn of natural numbers defined recursively:
F0 = 0
F1 = 1
Fn = Fn-1 + Fn-2, if n>1
Task
Write a function to generate the nth Fibonacci number.
Solutions can be iterative or recursive (though recursive solutions are generally considered too slow and are mostly used as an exercise in recursion).
The sequence is sometimes extended into negative numbers by using a straightforward inverse of the positive definition:
Fn = Fn+2 - Fn+1, if n<0
support for negative n in the solution is optional.
Related tasks
Fibonacci n-step number sequences
Leonardo numbers
References
Wikipedia, Fibonacci number
Wikipedia, Lucas number
MathWorld, Fibonacci Number
Some identities for r-Fibonacci numbers
OEIS Fibonacci numbers
OEIS Lucas numbers
| #Kabap | Kabap |
// Calculate the $n'th Fibonacci number
// Set this to how many in the sequence to generate
$n = 10;
// These are what hold the current calculation
$a = 0;
$b = 1;
// This holds the complete sequence that is generated
$sequence = "";
// Prepare a loop
$i = 0;
:calcnextnumber;
$i = $i++;
// Do the calculation for this loop iteration
$b = $a + $b;
$a = $b - $a;
// Add the result to the sequence
$sequence = $sequence << $a;
// Make the loop run a fixed number of times
if $i < $n; {
$sequence = $sequence << ", ";
goto calcnextnumber;
}
// Use the loop counter as the placeholder
$i--;
// Return the sequence
return = "Fibonacci number " << $i << " is " << $a << " (" << $sequence << ")";
|
http://rosettacode.org/wiki/Factors_of_an_integer | Factors of an integer |
Basic Data Operation
This is a basic data operation. It represents a fundamental action on a basic data type.
You may see other such operations in the Basic Data Operations category, or:
Integer Operations
Arithmetic |
Comparison
Boolean Operations
Bitwise |
Logical
String Operations
Concatenation |
Interpolation |
Comparison |
Matching
Memory Operations
Pointers & references |
Addresses
Task
Compute the factors of a positive integer.
These factors are the positive integers by which the number being factored can be divided to yield a positive integer result.
(Though the concepts function correctly for zero and negative integers, the set of factors of zero has countably infinite members, and the factors of negative integers can be obtained from the factors of related positive numbers without difficulty; this task does not require handling of either of these cases).
Note that every prime number has two factors: 1 and itself.
Related tasks
count in factors
prime decomposition
Sieve of Eratosthenes
primality by trial division
factors of a Mersenne number
trial factoring of a Mersenne number
partition an integer X into N primes
sequence of primes by Trial Division
sequence: smallest number greater than previous term with exactly n divisors
| #Standard_ML | Standard ML | fun printIntList ls =
(
List.app (fn n => print(Int.toString n ^ " ")) ls;
print "\n"
);
fun factors n =
let
fun factors'(n, k) =
if k > n then
[]
else if n mod k = 0 then
k :: factors'(n, k+1)
else
factors'(n, k+1)
in
factors'(n,1)
end;
|
http://rosettacode.org/wiki/Factors_of_an_integer | Factors of an integer |
Basic Data Operation
This is a basic data operation. It represents a fundamental action on a basic data type.
You may see other such operations in the Basic Data Operations category, or:
Integer Operations
Arithmetic |
Comparison
Boolean Operations
Bitwise |
Logical
String Operations
Concatenation |
Interpolation |
Comparison |
Matching
Memory Operations
Pointers & references |
Addresses
Task
Compute the factors of a positive integer.
These factors are the positive integers by which the number being factored can be divided to yield a positive integer result.
(Though the concepts function correctly for zero and negative integers, the set of factors of zero has countably infinite members, and the factors of negative integers can be obtained from the factors of related positive numbers without difficulty; this task does not require handling of either of these cases).
Note that every prime number has two factors: 1 and itself.
Related tasks
count in factors
prime decomposition
Sieve of Eratosthenes
primality by trial division
factors of a Mersenne number
trial factoring of a Mersenne number
partition an integer X into N primes
sequence of primes by Trial Division
sequence: smallest number greater than previous term with exactly n divisors
| #Swift | Swift | func factors(n: Int) -> [Int] {
return filter(1...n) { n % $0 == 0 }
} |
http://rosettacode.org/wiki/Execute_HQ9%2B | Execute HQ9+ | Task
Implement a HQ9+ interpreter or compiler.
| #Java | Java | function hq9plus(code) {
var out = '';
var acc = 0;
for (var i=0; i<code.length; i++) {
switch (code.charAt(i)) {
case 'H': out += "hello, world\n"; break;
case 'Q': out += code + "\n"; break;
case '9':
for (var j=99; j>1; j--) {
out += j + " bottles of beer on the wall, " + j + " bottles of beer.\n";
out += "Take one down and pass it around, " + (j-1) + " bottles of beer.\n\n";
}
out += "1 bottle of beer on the wall, 1 bottle of beer.\n" +
"Take one down and pass it around, no more bottles of beer on the wall.\n\n" +
"No more bottles of beer on the wall, no more bottles of beer.\n" +
"Go to the store and buy some more, 99 bottles of beer on the wall.\n";
break;
case '+': acc++; break;
}
}
return out;
} |
http://rosettacode.org/wiki/Execute_a_Markov_algorithm | Execute a Markov algorithm | Execute a Markov algorithm
You are encouraged to solve this task according to the task description, using any language you may know.
Task
Create an interpreter for a Markov Algorithm.
Rules have the syntax:
<ruleset> ::= ((<comment> | <rule>) <newline>+)*
<comment> ::= # {<any character>}
<rule> ::= <pattern> <whitespace> -> <whitespace> [.] <replacement>
<whitespace> ::= (<tab> | <space>) [<whitespace>]
There is one rule per line.
If there is a . (period) present before the <replacement>, then this is a terminating rule in which case the interpreter must halt execution.
A ruleset consists of a sequence of rules, with optional comments.
Rulesets
Use the following tests on entries:
Ruleset 1
# This rules file is extracted from Wikipedia:
# http://en.wikipedia.org/wiki/Markov_Algorithm
A -> apple
B -> bag
S -> shop
T -> the
the shop -> my brother
a never used -> .terminating rule
Sample text of:
I bought a B of As from T S.
Should generate the output:
I bought a bag of apples from my brother.
Ruleset 2
A test of the terminating rule
# Slightly modified from the rules on Wikipedia
A -> apple
B -> bag
S -> .shop
T -> the
the shop -> my brother
a never used -> .terminating rule
Sample text of:
I bought a B of As from T S.
Should generate:
I bought a bag of apples from T shop.
Ruleset 3
This tests for correct substitution order and may trap simple regexp based replacement routines if special regexp characters are not escaped.
# BNF Syntax testing rules
A -> apple
WWWW -> with
Bgage -> ->.*
B -> bag
->.* -> money
W -> WW
S -> .shop
T -> the
the shop -> my brother
a never used -> .terminating rule
Sample text of:
I bought a B of As W my Bgage from T S.
Should generate:
I bought a bag of apples with my money from T shop.
Ruleset 4
This tests for correct order of scanning of rules, and may trap replacement routines that scan in the wrong order. It implements a general unary multiplication engine. (Note that the input expression must be placed within underscores in this implementation.)
### Unary Multiplication Engine, for testing Markov Algorithm implementations
### By Donal Fellows.
# Unary addition engine
_+1 -> _1+
1+1 -> 11+
# Pass for converting from the splitting of multiplication into ordinary
# addition
1! -> !1
,! -> !+
_! -> _
# Unary multiplication by duplicating left side, right side times
1*1 -> x,@y
1x -> xX
X, -> 1,1
X1 -> 1X
_x -> _X
,x -> ,X
y1 -> 1y
y_ -> _
# Next phase of applying
1@1 -> x,@y
1@_ -> @_
,@_ -> !_
++ -> +
# Termination cleanup for addition
_1 -> 1
1+_ -> 1
_+_ ->
Sample text of:
_1111*11111_
should generate the output:
11111111111111111111
Ruleset 5
A simple Turing machine,
implementing a three-state busy beaver.
The tape consists of 0s and 1s, the states are A, B, C and H (for Halt), and the head position is indicated by writing the state letter before the character where the head is.
All parts of the initial tape the machine operates on have to be given in the input.
Besides demonstrating that the Markov algorithm is Turing-complete, it also made me catch a bug in the C++ implementation which wasn't caught by the first four rulesets.
# Turing machine: three-state busy beaver
#
# state A, symbol 0 => write 1, move right, new state B
A0 -> 1B
# state A, symbol 1 => write 1, move left, new state C
0A1 -> C01
1A1 -> C11
# state B, symbol 0 => write 1, move left, new state A
0B0 -> A01
1B0 -> A11
# state B, symbol 1 => write 1, move right, new state B
B1 -> 1B
# state C, symbol 0 => write 1, move left, new state B
0C0 -> B01
1C0 -> B11
# state C, symbol 1 => write 1, move left, halt
0C1 -> H01
1C1 -> H11
This ruleset should turn
000000A000000
into
00011H1111000
| #Groovy | Groovy | def markovInterpreterFor = { rules ->
def ruleMap = [:]
rules.eachLine { line ->
(line =~ /\s*(.+)\s->\s([.]?)(.+)\s*/).each { text, key, terminating, value ->
if (key.startsWith('#')) { return }
ruleMap[key] = [text: value, terminating: terminating]
}
}
[interpret: { text ->
def originalText = ''
while (originalText != text) {
originalText = text
for (Map.Entry e : ruleMap.entrySet()) {
if (text.indexOf(e.key) >= 0) {
text = text.replace(e.key, e.value.text)
if (e.value.terminating) {
return text
}
break
}
}
}
text
}]
} |
http://rosettacode.org/wiki/Exceptions/Catch_an_exception_thrown_in_a_nested_call | Exceptions/Catch an exception thrown in a nested call | Show how to create a user-defined exception and show how to catch an exception raised from several nested calls away.
Create two user-defined exceptions, U0 and U1.
Have function foo call function bar twice.
Have function bar call function baz.
Arrange for function baz to raise, or throw exception U0 on its first call, then exception U1 on its second.
Function foo should catch only exception U0, not U1.
Show/describe what happens when the program is run.
| #Haskell | Haskell | import Control.Monad.Error
import Control.Monad.Trans (lift)
-- Our "user-defined exception" tpe
data MyError = U0 | U1 | Other deriving (Eq, Read, Show)
-- Required for any error type
instance Error MyError where
noMsg = Other
strMsg _ = Other
-- Throwing and catching exceptions implies that we are working in a monad. In
-- this case, we use ErrorT to support our user-defined exceptions, wrapping
-- IO to be able to report the happenings. ('lift' converts ErrorT e IO a
-- actions into IO a actions.)
foo = do lift (putStrLn "foo")
mapM_ (\toThrow -> bar toThrow -- the protected call
`catchError` \caught -> -- the catch operation
-- ↓ what to do with it
case caught of U0 -> lift (putStrLn "foo caught U0")
_ -> throwError caught)
[U0, U1] -- the two exceptions to throw
bar toThrow = do lift (putStrLn " bar")
baz toThrow
baz toThrow = do lift (putStrLn " baz")
throwError toThrow
-- We cannot use exceptions without at some outer level choosing what to do
-- if an exception propagates all the way up. Here we just print the exception
-- if there was one.
main = do result <- runErrorT foo
case result of
Left e -> putStrLn ("Caught error at top level: " ++ show e)
Right v -> putStrLn ("Return value: " ++ show v) |
http://rosettacode.org/wiki/Exceptions/Catch_an_exception_thrown_in_a_nested_call | Exceptions/Catch an exception thrown in a nested call | Show how to create a user-defined exception and show how to catch an exception raised from several nested calls away.
Create two user-defined exceptions, U0 and U1.
Have function foo call function bar twice.
Have function bar call function baz.
Arrange for function baz to raise, or throw exception U0 on its first call, then exception U1 on its second.
Function foo should catch only exception U0, not U1.
Show/describe what happens when the program is run.
| #Icon_and_Unicon | Icon and Unicon | import Exceptions
class U0 : Exception()
method getMessage()
return "U0: " || (\message | "unknown")
end
end
class U1 : Exception()
method getMessage()
return "U1: " || (\message | "unknown")
end
end
procedure main()
# (Because Exceptions are not built into Unicon, uncaught
# exceptions are ignored. This clause will catch any
# exceptions not caught farther down in the code.)
case Try().call{ foo() } of {
Try().catch(): {
ex := Try().getException()
write(ex.getMessage(), ":\n", ex.getLocation())
}
}
end
procedure foo()
every 1|2 do {
case Try().call{ bar() } of {
Try().catch("U0"): {
ex := Try().getException()
write(ex.getMessage(), ":\n", ex.getLocation())
}
}
}
end
procedure bar()
return baz()
end
procedure baz()
initial U0().throw("First exception")
U1().throw("Second exception")
end |
http://rosettacode.org/wiki/Exceptions | Exceptions | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
This task is to give an example of an exception handling routine
and to "throw" a new exception.
Related task
Exceptions Through Nested Calls
| #E | E | def nameOf(arg :int) {
if (arg == 43) {
return "Bob"
} else {
throw("Who?")
}
}
def catching(arg) {
try {
return ["ok", nameOf(arg)]
} catch exceptionObj {
return ["notok", exceptionObj]
}
} |
http://rosettacode.org/wiki/Exceptions | Exceptions | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
This task is to give an example of an exception handling routine
and to "throw" a new exception.
Related task
Exceptions Through Nested Calls
| #Elena | Elena | class MyException : Exception
{
constructor new()
<= new("MyException raised");
} |
http://rosettacode.org/wiki/Execute_a_system_command | Execute a system command | Task
Run either the ls system command (dir on Windows), or the pause system command.
Related task
Get system command output
| #CMake | CMake | execute_process(COMMAND ls) |
http://rosettacode.org/wiki/Execute_a_system_command | Execute a system command | Task
Run either the ls system command (dir on Windows), or the pause system command.
Related task
Get system command output
| #COBOL | COBOL | CALL "SYSTEM" USING BY CONTENT "ls" |
http://rosettacode.org/wiki/Factorial | Factorial | Definitions
The factorial of 0 (zero) is defined as being 1 (unity).
The Factorial Function of a positive integer, n, is defined as the product of the sequence:
n, n-1, n-2, ... 1
Task
Write a function to return the factorial of a number.
Solutions can be iterative or recursive.
Support for trapping negative n errors is optional.
Related task
Primorial numbers
| #Apex | Apex | public static long fact(final Integer n) {
if (n < 0) {
System.debug('No negative numbers');
return 0;
}
long ans = 1;
for (Integer i = 1; i <= n; i++) {
ans *= i;
}
return ans;
} |
http://rosettacode.org/wiki/Exponentiation_operator | Exponentiation operator | Most programming languages have a built-in implementation of exponentiation.
Task
Re-implement integer exponentiation for both intint and floatint as both a procedure, and an operator (if your language supports operator definition).
If the language supports operator (or procedure) overloading, then an overloaded form should be provided for both intint and floatint variants.
Related tasks
Exponentiation order
arbitrary-precision integers (included)
Exponentiation with infix operators in (or operating on) the base
| #J | J | exp =: */@:#~
10 exp 3
1000
10 exp 0
1 |
http://rosettacode.org/wiki/Exponentiation_operator | Exponentiation operator | Most programming languages have a built-in implementation of exponentiation.
Task
Re-implement integer exponentiation for both intint and floatint as both a procedure, and an operator (if your language supports operator definition).
If the language supports operator (or procedure) overloading, then an overloaded form should be provided for both intint and floatint variants.
Related tasks
Exponentiation order
arbitrary-precision integers (included)
Exponentiation with infix operators in (or operating on) the base
| #Java | Java | public class Exp{
public static void main(String[] args){
System.out.println(pow(2,30));
System.out.println(pow(2.0,30)); //tests
System.out.println(pow(2.0,-2));
}
public static double pow(double base, int exp){
if(exp < 0) return 1 / pow(base, -exp);
double ans = 1.0;
for(;exp > 0;--exp) ans *= base;
return ans;
}
} |
http://rosettacode.org/wiki/Extend_your_language | Extend your language | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
Some programming languages allow you to extend the language. While this can be done to a certain degree in most languages (e.g. by using macros), other languages go much further. Most notably in the Forth and Lisp families, programming per se is done by extending the language without any formal distinction between built-in and user-defined elements.
If your language supports it, show how to introduce a new flow control mechanism. A practical and useful example is a four-way branch:
Occasionally, code must be written that depends on two conditions, resulting in up to four branches (depending on whether both, only the first, only the second, or none of the conditions are "true"). In a C-like language this could look like the following:
if (condition1isTrue) {
if (condition2isTrue)
bothConditionsAreTrue();
else
firstConditionIsTrue();
}
else if (condition2isTrue)
secondConditionIsTrue();
else
noConditionIsTrue();
Besides being rather cluttered, the statement(s) for 'condition2isTrue' must be written down twice. If 'condition2isTrue' were a lengthy and involved expression, it would be quite unreadable, and the code generated by the compiler might be unnecessarily large.
This can be improved by introducing a new keyword if2. It is similar to if, but takes two conditional statements instead of one, and up to three 'else' statements. One proposal (in pseudo-C syntax) might be:
if2 (condition1isTrue) (condition2isTrue)
bothConditionsAreTrue();
else1
firstConditionIsTrue();
else2
secondConditionIsTrue();
else
noConditionIsTrue();
Pick the syntax which suits your language. The keywords 'else1' and 'else2' are just examples. The new conditional expression should look, nest and behave analogously to the language's built-in 'if' statement.
| #PARI.2FGP | PARI/GP | if2(c1,c2,tt,tf,ft,ff)={
if(c1,
if(c2,tt,tf)
,
if(c2,ft,ff)
)
}; |
http://rosettacode.org/wiki/Extend_your_language | Extend your language | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
Some programming languages allow you to extend the language. While this can be done to a certain degree in most languages (e.g. by using macros), other languages go much further. Most notably in the Forth and Lisp families, programming per se is done by extending the language without any formal distinction between built-in and user-defined elements.
If your language supports it, show how to introduce a new flow control mechanism. A practical and useful example is a four-way branch:
Occasionally, code must be written that depends on two conditions, resulting in up to four branches (depending on whether both, only the first, only the second, or none of the conditions are "true"). In a C-like language this could look like the following:
if (condition1isTrue) {
if (condition2isTrue)
bothConditionsAreTrue();
else
firstConditionIsTrue();
}
else if (condition2isTrue)
secondConditionIsTrue();
else
noConditionIsTrue();
Besides being rather cluttered, the statement(s) for 'condition2isTrue' must be written down twice. If 'condition2isTrue' were a lengthy and involved expression, it would be quite unreadable, and the code generated by the compiler might be unnecessarily large.
This can be improved by introducing a new keyword if2. It is similar to if, but takes two conditional statements instead of one, and up to three 'else' statements. One proposal (in pseudo-C syntax) might be:
if2 (condition1isTrue) (condition2isTrue)
bothConditionsAreTrue();
else1
firstConditionIsTrue();
else2
secondConditionIsTrue();
else
noConditionIsTrue();
Pick the syntax which suits your language. The keywords 'else1' and 'else2' are just examples. The new conditional expression should look, nest and behave analogously to the language's built-in 'if' statement.
| #Perl | Perl |
#!/usr/bin/perl
use warnings;
use strict;
use v5.10;
=for starters
Syntax:
if2 condition1, condition2, then2 {
# both conditions are true
}
else1 {
# only condition1 is true
}
else2 {
# only condition2 is true
}
orelse {
# neither condition is true
};
Any (but not all) of the `then' and `else' clauses can be omitted, and else1
and else2 can be specified in either order.
This extension is imperfect in several ways:
* A normal if-statement uses round brackets, but this syntax forbids them.
* Perl doesn't have a `then' keyword; if it did, it probably wouldn't be
preceded by a comma.
* Unless it's the last thing in a block, the whole structure must be followed
by a semicolon.
* Error messages appear at runtime, not compile time, and they don't show the
line where the user's syntax error occurred.
We could solve most of these problems with a source filter, but those are
dangerous. Can anyone else do better? Feel free to improve or replace.
=cut
# All the new `keywords' are in fact functions. Most of them return lists
# of four closures, one of which is then executed by if2. Here are indexes into
# these lists:
use constant {
IdxThen => 0,
IdxElse1 => 1,
IdxElse2 => 2,
IdxOrElse => 3
};
# Most of the magic is in the (&) prototype, which lets a function accept a
# closure marked by nothing except braces.
sub orelse(&) {
my $clause = shift;
return undef, undef, undef, $clause;
}
sub else2(&@) {
my $clause = shift;
die "Can't have two `else2' clauses"
if defined $_[IdxElse2];
return (undef, $_[IdxElse1], $clause, $_[IdxOrElse]);
}
sub else1(&@) {
my $clause = shift;
die "Can't have two `else1' clauses"
if defined $_[IdxElse1];
return (undef, $clause, $_[IdxElse2], $_[IdxOrElse]);
}
sub then2(&@) {
die "Can't have two `then2' clauses"
if defined $_[1+IdxThen];
splice @_, 1+IdxThen, 1;
return @_;
}
# Here, we collect the two conditions and four closures (some of which will be
# undefined if some clauses are missing). We work out which of the four
# clauses (closures) to call, and call it if it exists.
use constant {
# Defining True and False is almost always bad practice, but here we
# have a valid reason.
True => (0 == 0),
False => (0 == 1)
};
sub if2($$@) {
my $cond1 = !!shift; # Convert to Boolean to guarantee matching
my $cond2 = !!shift; # against either True or False
die "if2 must be followed by then2, else1, else2, &/or orelse"
if @_ != 4
or grep {defined and ref $_ ne 'CODE'} @_;
my $index;
if (!$cond1 && !$cond2) {$index = IdxOrElse}
if (!$cond1 && $cond2) {$index = IdxElse2 }
if ( $cond1 && !$cond2) {$index = IdxElse1 }
if ( $cond1 && $cond2) {$index = IdxThen }
my $closure = $_[$index];
&$closure if defined $closure;
}
# This is test code. You can play with it by deleting up to three of the
# four clauses.
sub test_bits($) {
(my $n) = @_;
print "Testing $n: ";
if2 $n & 1, $n & 2, then2 {
say "Both bits 0 and 1 are set";
}
else1 {
say "Only bit 0 is set";
}
else2 {
say "Only bit 1 is set";
}
orelse {
say "Neither bit is set";
}
}
test_bits $_ for 0 .. 7;
|
http://rosettacode.org/wiki/FizzBuzz | FizzBuzz | Task
Write a program that prints the integers from 1 to 100 (inclusive).
But:
for multiples of three, print Fizz (instead of the number)
for multiples of five, print Buzz (instead of the number)
for multiples of both three and five, print FizzBuzz (instead of the number)
The FizzBuzz problem was presented as the lowest level of comprehension required to illustrate adequacy.
Also see
(a blog) dont-overthink-fizzbuzz
(a blog) fizzbuzz-the-programmers-stairway-to-heaven
| #Ruby_with_RSpec | Ruby with RSpec |
require 'fizzbuzz'
describe 'FizzBuzz' do
context 'knows that a number is divisible by' do
it '3' do
expect(is_divisible_by_three?(3)).to be_true
end
it '5' do
expect(is_divisible_by_five?(5)).to be_true
end
it '15' do
expect(is_divisible_by_fifteen?(15)).to be_true
end
end
context 'knows that a number is not divisible by' do
it '3' do
expect(is_divisible_by_three?(1)).not_to be_true
end
it '5' do
expect(is_divisible_by_five?(1)).not_to be_true
end
it '15' do
expect(is_divisible_by_fifteen?(1)).not_to be_true
end
end
context 'while playing the game it returns' do
it 'the number' do
expect(fizzbuzz(1)).to eq 1
end
it 'Fizz' do
expect(fizzbuzz(3)).to eq 'Fizz'
end
it 'Buzz' do
expect(fizzbuzz(5)).to eq 'Buzz'
end
it 'FizzBuzz' do
expect(fizzbuzz(15)).to eq 'FizzBuzz'
end
end
end
|
http://rosettacode.org/wiki/Extensible_prime_generator | Extensible prime generator | Task
Write a generator of prime numbers, in order, that will automatically adjust to accommodate the generation of any reasonably high prime.
The routine should demonstrably rely on either:
Being based on an open-ended counter set to count without upper limit other than system or programming language limits. In this case, explain where this counter is in the code.
Being based on a limit that is extended automatically. In this case, choose a small limit that ensures the limit will be passed when generating some of the values to be asked for below.
If other methods of creating an extensible prime generator are used, the algorithm's means of extensibility/lack of limits should be stated.
The routine should be used to:
Show the first twenty primes.
Show the primes between 100 and 150.
Show the number of primes between 7,700 and 8,000.
Show the 10,000th prime.
Show output on this page.
Note: You may reference code already on this site if it is written to be imported/included, then only the code necessary for import and the performance of this task need be shown. (It is also important to leave a forward link on the referenced tasks entry so that later editors know that the code is used for multiple tasks).
Note 2: If a languages in-built prime generator is extensible or is guaranteed to generate primes up to a system limit, (231 or memory overflow for example), then this may be used as long as an explanation of the limits of the prime generator is also given. (Which may include a link to/excerpt from, language documentation).
Note 3:The task is written so it may be useful in solving the task Emirp primes as well as others (depending on its efficiency).
Reference
Prime Numbers. Website with large count of primes.
| #Perl | Perl | use Math::Prime::Util qw(nth_prime prime_count primes);
# Direct solutions.
# primes([start],end) returns an array reference with all primes in the range
# prime_count([start],end) uses sieving or LMO to return fast prime counts
# nth_prime(n) does just that. It runs quite fast for native size inputs.
say "First 20: ", join(" ", @{primes(nth_prime(20))});
say "Between 100 and 150: ", join(" ", @{primes(100,150)});
say prime_count(7700,8000), " primes between 7700 and 8000";
say "${_}th prime: ", nth_prime($_) for map { 10**$_ } 1..8; |
http://rosettacode.org/wiki/Execute_Brain**** | Execute Brain**** | Execute Brain**** is an implementation of Brainf***.
Other implementations of Brainf***.
RCBF is a set of Brainf*** compilers and interpreters written for Rosetta Code in a variety of languages.
Below are links to each of the versions of RCBF.
An implementation need only properly implement the following instructions:
Command
Description
>
Move the pointer to the right
<
Move the pointer to the left
+
Increment the memory cell under the pointer
-
Decrement the memory cell under the pointer
.
Output the character signified by the cell at the pointer
,
Input a character and store it in the cell at the pointer
[
Jump past the matching ] if the cell under the pointer is 0
]
Jump back to the matching [ if the cell under the pointer is nonzero
Any cell size is allowed, EOF (End-O-File) support is optional, as is whether you have bounded or unbounded memory.
| #Arturo | Arturo | ;
; Brainf*ck compiler
; In Arturo
;
Tape: [0]
DataPointer: new 0
InstructionPointer: new 0
; Look for jumps in Code an register them
; in the Jumps table
precomputeJumps: function [][
vstack: new []
jumphash: new #[]
instrPointer: 0
while [instrPointer<CodeLength] [
command: get split Code instrPointer
if? command="[" -> 'vstack ++ instrPointer
else [
if command="]" [
target: last vstack
chop 'vstack
jumphash\[target]: instrPointer
jumphash\[instrPointer]: target
]
]
instrPointer: instrPointer+1
]
jumphash
]
; Check if current state is valid
StateIsValid: function [][
all? @[
0 =< DataPointer
DataPointer < size Tape
0 =< InstructionPointer
InstructionPointer < CodeLength
]
]
; Compile the program
interpret: function [].export:[DataPointer,InstructionPointer,Tape][
while [StateIsValid][
command: get split Code InstructionPointer
case [command=]
when? ["+"] -> Tape\[DataPointer]: Tape\[DataPointer]+1
when? ["-"] -> Tape\[DataPointer]: Tape\[DataPointer]-1
when? [">"] [
inc 'DataPointer
if DataPointer = size Tape -> Tape: Tape ++ 0
]
when? ["<"] -> dec 'DataPointer
when? ["."] -> prints to :string to :char Tape\[DataPointer]
when? [","][
inp: to :integer input ""
if inp=13 -> inp: 10
if inp=3 -> panic "something went wrong!"
set Tape DataPointer inp
]
when? ["["] ->
if 0 = get Tape DataPointer [ InstructionPointer: new get Jumps InstructionPointer ]
when? ["]"] ->
if 0 <> get Tape DataPointer [
InstructionPointer: new get Jumps InstructionPointer
]
inc 'InstructionPointer
]
]
Code: ""
if? 1>size arg -> Code: "++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>."
else -> Code: read arg\0
CodeLength: size Code
Jumps: precomputeJumps
interpret |
http://rosettacode.org/wiki/Evolutionary_algorithm | Evolutionary algorithm | Starting with:
The target string: "METHINKS IT IS LIKE A WEASEL".
An array of random characters chosen from the set of upper-case letters together with the space, and of the same length as the target string. (Call it the parent).
A fitness function that computes the ‘closeness’ of its argument to the target string.
A mutate function that given a string and a mutation rate returns a copy of the string, with some characters probably mutated.
While the parent is not yet the target:
copy the parent C times, each time allowing some random probability that another character might be substituted using mutate.
Assess the fitness of the parent and all the copies to the target and make the most fit string the new parent, discarding the others.
repeat until the parent converges, (hopefully), to the target.
See also
Wikipedia entry: Weasel algorithm.
Wikipedia entry: Evolutionary algorithm.
Note: to aid comparison, try and ensure the variables and functions mentioned in the task description appear in solutions
A cursory examination of a few of the solutions reveals that the instructions have not been followed rigorously in some solutions. Specifically,
While the parent is not yet the target:
copy the parent C times, each time allowing some random probability that another character might be substituted using mutate.
Note that some of the the solutions given retain characters in the mutated string that are correct in the target string. However, the instruction above does not state to retain any of the characters while performing the mutation. Although some may believe to do so is implied from the use of "converges"
(:* repeat until the parent converges, (hopefully), to the target.
Strictly speaking, the new parent should be selected from the new pool of mutations, and then the new parent used to generate the next set of mutations with parent characters getting retained only by not being mutated. It then becomes possible that the new set of mutations has no member that is fitter than the parent!
As illustration of this error, the code for 8th has the following remark.
Create a new string based on the TOS, changing randomly any characters which
don't already match the target:
NOTE: this has been changed, the 8th version is completely random now
Clearly, this algo will be applying the mutation function only to the parent characters that don't match to the target characters!
To ensure that the new parent is never less fit than the prior parent, both the parent and all of the latest mutations are subjected to the fitness test to select the next parent.
| #AutoHotkey | AutoHotkey | output := ""
target := "METHINKS IT IS LIKE A WEASEL"
targetLen := StrLen(target)
Loop, 26
possibilities_%A_Index% := Chr(A_Index+64) ; A-Z
possibilities_27 := " "
C := 100
parent := ""
Loop, %targetLen%
{
Random, randomNum, 1, 27
parent .= possibilities_%randomNum%
}
Loop,
{
If (target = parent)
Break
If (Mod(A_Index,10) = 0)
output .= A_Index ": " parent ", fitness: " fitness(parent, target) "`n"
bestFit := 0
Loop, %C%
If ((fitness := fitness(spawn := mutate(parent), target)) > bestFit)
bestSpawn := spawn , bestFit := fitness
parent := bestFit > fitness(parent, target) ? bestSpawn : parent
iter := A_Index
}
output .= parent ", " iter
MsgBox, % output
ExitApp
mutate(parent) {
local output, replaceChar, newChar
output := ""
Loop, %targetLen%
{
Random, replaceChar, 0, 9
If (replaceChar != 0)
output .= SubStr(parent, A_Index, 1)
else
{
Random, newChar, 1, 27
output .= possibilities_%newChar%
}
}
Return output
}
fitness(string, target) {
totalFit := 0
Loop, % StrLen(string)
If (SubStr(string, A_Index, 1) = SubStr(target, A_Index, 1))
totalFit++
Return totalFit
} |
http://rosettacode.org/wiki/Fibonacci_sequence | Fibonacci sequence | The Fibonacci sequence is a sequence Fn of natural numbers defined recursively:
F0 = 0
F1 = 1
Fn = Fn-1 + Fn-2, if n>1
Task
Write a function to generate the nth Fibonacci number.
Solutions can be iterative or recursive (though recursive solutions are generally considered too slow and are mostly used as an exercise in recursion).
The sequence is sometimes extended into negative numbers by using a straightforward inverse of the positive definition:
Fn = Fn+2 - Fn+1, if n<0
support for negative n in the solution is optional.
Related tasks
Fibonacci n-step number sequences
Leonardo numbers
References
Wikipedia, Fibonacci number
Wikipedia, Lucas number
MathWorld, Fibonacci Number
Some identities for r-Fibonacci numbers
OEIS Fibonacci numbers
OEIS Lucas numbers
| #Klingphix | Klingphix | :Fibonacci
dup 0 less
( ["Invalid argument"]
[1 1 rot 2 sub [drop over over add] for]
) if
;
30 Fibonacci pstack print nl
msec print nl
"bertlham " input |
http://rosettacode.org/wiki/Factors_of_an_integer | Factors of an integer |
Basic Data Operation
This is a basic data operation. It represents a fundamental action on a basic data type.
You may see other such operations in the Basic Data Operations category, or:
Integer Operations
Arithmetic |
Comparison
Boolean Operations
Bitwise |
Logical
String Operations
Concatenation |
Interpolation |
Comparison |
Matching
Memory Operations
Pointers & references |
Addresses
Task
Compute the factors of a positive integer.
These factors are the positive integers by which the number being factored can be divided to yield a positive integer result.
(Though the concepts function correctly for zero and negative integers, the set of factors of zero has countably infinite members, and the factors of negative integers can be obtained from the factors of related positive numbers without difficulty; this task does not require handling of either of these cases).
Note that every prime number has two factors: 1 and itself.
Related tasks
count in factors
prime decomposition
Sieve of Eratosthenes
primality by trial division
factors of a Mersenne number
trial factoring of a Mersenne number
partition an integer X into N primes
sequence of primes by Trial Division
sequence: smallest number greater than previous term with exactly n divisors
| #Tailspin | Tailspin |
[1..351 -> \(when <?(351 mod $ <=0>)> do $! \)] -> !OUT::write
|
http://rosettacode.org/wiki/Factors_of_an_integer | Factors of an integer |
Basic Data Operation
This is a basic data operation. It represents a fundamental action on a basic data type.
You may see other such operations in the Basic Data Operations category, or:
Integer Operations
Arithmetic |
Comparison
Boolean Operations
Bitwise |
Logical
String Operations
Concatenation |
Interpolation |
Comparison |
Matching
Memory Operations
Pointers & references |
Addresses
Task
Compute the factors of a positive integer.
These factors are the positive integers by which the number being factored can be divided to yield a positive integer result.
(Though the concepts function correctly for zero and negative integers, the set of factors of zero has countably infinite members, and the factors of negative integers can be obtained from the factors of related positive numbers without difficulty; this task does not require handling of either of these cases).
Note that every prime number has two factors: 1 and itself.
Related tasks
count in factors
prime decomposition
Sieve of Eratosthenes
primality by trial division
factors of a Mersenne number
trial factoring of a Mersenne number
partition an integer X into N primes
sequence of primes by Trial Division
sequence: smallest number greater than previous term with exactly n divisors
| #Tcl | Tcl | proc factors {n} {
set factors {}
for {set i 1} {$i <= sqrt($n)} {incr i} {
if {$n % $i == 0} {
lappend factors $i [expr {$n / $i}]
}
}
return [lsort -unique -integer $factors]
}
puts [factors 64]
puts [factors 45]
puts [factors 53] |
http://rosettacode.org/wiki/Execute_HQ9%2B | Execute HQ9+ | Task
Implement a HQ9+ interpreter or compiler.
| #JavaScript | JavaScript | function hq9plus(code) {
var out = '';
var acc = 0;
for (var i=0; i<code.length; i++) {
switch (code.charAt(i)) {
case 'H': out += "hello, world\n"; break;
case 'Q': out += code + "\n"; break;
case '9':
for (var j=99; j>1; j--) {
out += j + " bottles of beer on the wall, " + j + " bottles of beer.\n";
out += "Take one down and pass it around, " + (j-1) + " bottles of beer.\n\n";
}
out += "1 bottle of beer on the wall, 1 bottle of beer.\n" +
"Take one down and pass it around, no more bottles of beer on the wall.\n\n" +
"No more bottles of beer on the wall, no more bottles of beer.\n" +
"Go to the store and buy some more, 99 bottles of beer on the wall.\n";
break;
case '+': acc++; break;
}
}
return out;
} |
http://rosettacode.org/wiki/Execute_a_Markov_algorithm | Execute a Markov algorithm | Execute a Markov algorithm
You are encouraged to solve this task according to the task description, using any language you may know.
Task
Create an interpreter for a Markov Algorithm.
Rules have the syntax:
<ruleset> ::= ((<comment> | <rule>) <newline>+)*
<comment> ::= # {<any character>}
<rule> ::= <pattern> <whitespace> -> <whitespace> [.] <replacement>
<whitespace> ::= (<tab> | <space>) [<whitespace>]
There is one rule per line.
If there is a . (period) present before the <replacement>, then this is a terminating rule in which case the interpreter must halt execution.
A ruleset consists of a sequence of rules, with optional comments.
Rulesets
Use the following tests on entries:
Ruleset 1
# This rules file is extracted from Wikipedia:
# http://en.wikipedia.org/wiki/Markov_Algorithm
A -> apple
B -> bag
S -> shop
T -> the
the shop -> my brother
a never used -> .terminating rule
Sample text of:
I bought a B of As from T S.
Should generate the output:
I bought a bag of apples from my brother.
Ruleset 2
A test of the terminating rule
# Slightly modified from the rules on Wikipedia
A -> apple
B -> bag
S -> .shop
T -> the
the shop -> my brother
a never used -> .terminating rule
Sample text of:
I bought a B of As from T S.
Should generate:
I bought a bag of apples from T shop.
Ruleset 3
This tests for correct substitution order and may trap simple regexp based replacement routines if special regexp characters are not escaped.
# BNF Syntax testing rules
A -> apple
WWWW -> with
Bgage -> ->.*
B -> bag
->.* -> money
W -> WW
S -> .shop
T -> the
the shop -> my brother
a never used -> .terminating rule
Sample text of:
I bought a B of As W my Bgage from T S.
Should generate:
I bought a bag of apples with my money from T shop.
Ruleset 4
This tests for correct order of scanning of rules, and may trap replacement routines that scan in the wrong order. It implements a general unary multiplication engine. (Note that the input expression must be placed within underscores in this implementation.)
### Unary Multiplication Engine, for testing Markov Algorithm implementations
### By Donal Fellows.
# Unary addition engine
_+1 -> _1+
1+1 -> 11+
# Pass for converting from the splitting of multiplication into ordinary
# addition
1! -> !1
,! -> !+
_! -> _
# Unary multiplication by duplicating left side, right side times
1*1 -> x,@y
1x -> xX
X, -> 1,1
X1 -> 1X
_x -> _X
,x -> ,X
y1 -> 1y
y_ -> _
# Next phase of applying
1@1 -> x,@y
1@_ -> @_
,@_ -> !_
++ -> +
# Termination cleanup for addition
_1 -> 1
1+_ -> 1
_+_ ->
Sample text of:
_1111*11111_
should generate the output:
11111111111111111111
Ruleset 5
A simple Turing machine,
implementing a three-state busy beaver.
The tape consists of 0s and 1s, the states are A, B, C and H (for Halt), and the head position is indicated by writing the state letter before the character where the head is.
All parts of the initial tape the machine operates on have to be given in the input.
Besides demonstrating that the Markov algorithm is Turing-complete, it also made me catch a bug in the C++ implementation which wasn't caught by the first four rulesets.
# Turing machine: three-state busy beaver
#
# state A, symbol 0 => write 1, move right, new state B
A0 -> 1B
# state A, symbol 1 => write 1, move left, new state C
0A1 -> C01
1A1 -> C11
# state B, symbol 0 => write 1, move left, new state A
0B0 -> A01
1B0 -> A11
# state B, symbol 1 => write 1, move right, new state B
B1 -> 1B
# state C, symbol 0 => write 1, move left, new state B
0C0 -> B01
1C0 -> B11
# state C, symbol 1 => write 1, move left, halt
0C1 -> H01
1C1 -> H11
This ruleset should turn
000000A000000
into
00011H1111000
| #Haskell | Haskell | import Data.List (isPrefixOf)
import Data.Maybe (catMaybes)
import Control.Monad
import Text.ParserCombinators.Parsec
import System.IO
import System.Environment (getArgs)
main = do
args <- getArgs
unless (length args == 1) $
fail "Please provide exactly one source file as an argument."
let sourcePath = head args
source <- readFile sourcePath
input <- getContents
case parse markovParser sourcePath source of
Right rules -> putStr $ runMarkov rules input
Left err -> hPutStrLn stderr $ "Parse error at " ++ show err
data Rule = Rule
{from :: String, terminating :: Bool, to :: String}
markovParser :: Parser [Rule]
markovParser = liftM catMaybes $
(comment <|> rule) `sepEndBy` many1 newline
where comment = char '#' >> skipMany nonnl >> return Nothing
rule = liftM Just $ liftM3 Rule
(manyTill (nonnl <?> "pattern character") $ try arrow)
(succeeds $ char '.')
(many nonnl)
arrow = ws >> string "->" >> ws <?> "whitespace-delimited arrow"
nonnl = noneOf "\n"
ws = many1 $ oneOf " \t"
succeeds p = option False $ p >> return True
runMarkov :: [Rule] -> String -> String
runMarkov rules s = f rules s
where f [] s = s
f (Rule from terminating to : rs) s = g "" s
where g _ "" = f rs s
g before ahead@(a : as) = if from `isPrefixOf` ahead
then let new = reverse before ++ to ++ drop (length from) ahead
in if terminating then new else f rules new
else g (a : before) as |
http://rosettacode.org/wiki/Exceptions/Catch_an_exception_thrown_in_a_nested_call | Exceptions/Catch an exception thrown in a nested call | Show how to create a user-defined exception and show how to catch an exception raised from several nested calls away.
Create two user-defined exceptions, U0 and U1.
Have function foo call function bar twice.
Have function bar call function baz.
Arrange for function baz to raise, or throw exception U0 on its first call, then exception U1 on its second.
Function foo should catch only exception U0, not U1.
Show/describe what happens when the program is run.
| #Io | Io | U0 := Exception clone
U1 := Exception clone
foo := method(
for(i,1,2,
try(
bar(i)
)catch( U0,
"foo caught U0" print
)pass
)
)
bar := method(n,
baz(n)
)
baz := method(n,
if(n == 1,U0,U1) raise("baz with n = #{n}" interpolate)
)
foo |
http://rosettacode.org/wiki/Exceptions/Catch_an_exception_thrown_in_a_nested_call | Exceptions/Catch an exception thrown in a nested call | Show how to create a user-defined exception and show how to catch an exception raised from several nested calls away.
Create two user-defined exceptions, U0 and U1.
Have function foo call function bar twice.
Have function bar call function baz.
Arrange for function baz to raise, or throw exception U0 on its first call, then exception U1 on its second.
Function foo should catch only exception U0, not U1.
Show/describe what happens when the program is run.
| #J | J | main=: monad define
smoutput 'main'
try. foo ''
catcht. smoutput 'main caught ',type_jthrow_
end.
)
foo=: monad define
smoutput ' foo'
for_i. 0 1 do.
try. bar i
catcht. if. type_jthrow_-:'U0' do. smoutput ' foo caught ',type_jthrow_ else. throw. end.
end.
end.
)
bar=: baz [ smoutput bind ' bar'
baz=: monad define
smoutput ' baz'
type_jthrow_=: 'U',":y throw.
) |
http://rosettacode.org/wiki/Exceptions | Exceptions | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
This task is to give an example of an exception handling routine
and to "throw" a new exception.
Related task
Exceptions Through Nested Calls
| #Erlang | Erlang |
-module( exceptions ).
-export( [task/0] ).
task() ->
try
erlang:throw( new_exception )
catch
_:Exception -> io:fwrite( "Catched ~p~n", [Exception] )
end.
|
http://rosettacode.org/wiki/Exceptions | Exceptions | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
This task is to give an example of an exception handling routine
and to "throw" a new exception.
Related task
Exceptions Through Nested Calls
| #Factor | Factor | "Install Linux, Problem Solved" throw
TUPLE: velociraptor ;
\ velociraptor new throw |
http://rosettacode.org/wiki/Execute_a_system_command | Execute a system command | Task
Run either the ls system command (dir on Windows), or the pause system command.
Related task
Get system command output
| #CoffeeScript | CoffeeScript |
{ spawn } = require 'child_process'
ls = spawn 'ls'
ls.stdout.on 'data', ( data ) -> console.log "Output: #{ data }"
ls.stderr.on 'data', ( data ) -> console.error "Error: #{ data }"
ls.on 'close', -> console.log "'ls' has finished executing."
|
http://rosettacode.org/wiki/Execute_a_system_command | Execute a system command | Task
Run either the ls system command (dir on Windows), or the pause system command.
Related task
Get system command output
| #Common_Lisp | Common Lisp | (with-output-to-string (stream) (extensions:run-program "ls" nil :output stream)) |
http://rosettacode.org/wiki/Factorial | Factorial | Definitions
The factorial of 0 (zero) is defined as being 1 (unity).
The Factorial Function of a positive integer, n, is defined as the product of the sequence:
n, n-1, n-2, ... 1
Task
Write a function to return the factorial of a number.
Solutions can be iterative or recursive.
Support for trapping negative n errors is optional.
Related task
Primorial numbers
| #APL | APL | !6
720 |
http://rosettacode.org/wiki/Exponentiation_operator | Exponentiation operator | Most programming languages have a built-in implementation of exponentiation.
Task
Re-implement integer exponentiation for both intint and floatint as both a procedure, and an operator (if your language supports operator definition).
If the language supports operator (or procedure) overloading, then an overloaded form should be provided for both intint and floatint variants.
Related tasks
Exponentiation order
arbitrary-precision integers (included)
Exponentiation with infix operators in (or operating on) the base
| #JavaScript | JavaScript | function pow(base, exp) {
if (exp != Math.floor(exp))
throw "exponent must be an integer";
if (exp < 0)
return 1 / pow(base, -exp);
var ans = 1;
while (exp > 0) {
ans *= base;
exp--;
}
return ans;
} |
http://rosettacode.org/wiki/Exponentiation_operator | Exponentiation operator | Most programming languages have a built-in implementation of exponentiation.
Task
Re-implement integer exponentiation for both intint and floatint as both a procedure, and an operator (if your language supports operator definition).
If the language supports operator (or procedure) overloading, then an overloaded form should be provided for both intint and floatint variants.
Related tasks
Exponentiation order
arbitrary-precision integers (included)
Exponentiation with infix operators in (or operating on) the base
| #jq | jq | # 0^0 => 1
# NOTE: jq converts very large integers to floats.
# This implementation uses reduce to avoid deep recursion
def power_int(n):
if n == 0 then 1
elif . == 0 then 0
elif n < 0 then 1/power_int(-n)
elif ((n | floor) == n) then
( (n % 2) | if . == 0 then 1 else -1 end ) as $sign
| if (. == -1) then $sign
elif . < 0 then (( -(.) | power_int(n) ) * $sign)
else . as $in | reduce range(1;n) as $i ($in; . * $in)
end
else error("This is a toy implementation that requires n be integral")
end ; |
http://rosettacode.org/wiki/Extend_your_language | Extend your language | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
Some programming languages allow you to extend the language. While this can be done to a certain degree in most languages (e.g. by using macros), other languages go much further. Most notably in the Forth and Lisp families, programming per se is done by extending the language without any formal distinction between built-in and user-defined elements.
If your language supports it, show how to introduce a new flow control mechanism. A practical and useful example is a four-way branch:
Occasionally, code must be written that depends on two conditions, resulting in up to four branches (depending on whether both, only the first, only the second, or none of the conditions are "true"). In a C-like language this could look like the following:
if (condition1isTrue) {
if (condition2isTrue)
bothConditionsAreTrue();
else
firstConditionIsTrue();
}
else if (condition2isTrue)
secondConditionIsTrue();
else
noConditionIsTrue();
Besides being rather cluttered, the statement(s) for 'condition2isTrue' must be written down twice. If 'condition2isTrue' were a lengthy and involved expression, it would be quite unreadable, and the code generated by the compiler might be unnecessarily large.
This can be improved by introducing a new keyword if2. It is similar to if, but takes two conditional statements instead of one, and up to three 'else' statements. One proposal (in pseudo-C syntax) might be:
if2 (condition1isTrue) (condition2isTrue)
bothConditionsAreTrue();
else1
firstConditionIsTrue();
else2
secondConditionIsTrue();
else
noConditionIsTrue();
Pick the syntax which suits your language. The keywords 'else1' and 'else2' are just examples. The new conditional expression should look, nest and behave analogously to the language's built-in 'if' statement.
| #Phix | Phix | switch {condition1,condition2} do
case {true,true}:
case {true,false}:
case {false,true}:
case {false,false}:
end switch
|
http://rosettacode.org/wiki/Extend_your_language | Extend your language | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
Some programming languages allow you to extend the language. While this can be done to a certain degree in most languages (e.g. by using macros), other languages go much further. Most notably in the Forth and Lisp families, programming per se is done by extending the language without any formal distinction between built-in and user-defined elements.
If your language supports it, show how to introduce a new flow control mechanism. A practical and useful example is a four-way branch:
Occasionally, code must be written that depends on two conditions, resulting in up to four branches (depending on whether both, only the first, only the second, or none of the conditions are "true"). In a C-like language this could look like the following:
if (condition1isTrue) {
if (condition2isTrue)
bothConditionsAreTrue();
else
firstConditionIsTrue();
}
else if (condition2isTrue)
secondConditionIsTrue();
else
noConditionIsTrue();
Besides being rather cluttered, the statement(s) for 'condition2isTrue' must be written down twice. If 'condition2isTrue' were a lengthy and involved expression, it would be quite unreadable, and the code generated by the compiler might be unnecessarily large.
This can be improved by introducing a new keyword if2. It is similar to if, but takes two conditional statements instead of one, and up to three 'else' statements. One proposal (in pseudo-C syntax) might be:
if2 (condition1isTrue) (condition2isTrue)
bothConditionsAreTrue();
else1
firstConditionIsTrue();
else2
secondConditionIsTrue();
else
noConditionIsTrue();
Pick the syntax which suits your language. The keywords 'else1' and 'else2' are just examples. The new conditional expression should look, nest and behave analogously to the language's built-in 'if' statement.
| #PHL | PHL | module stmts;
import phl::lang::io;
/* LinkedList --> Each element contains a condition */
struct @ConditionalChain {
field @Boolean cond;
field @ConditionalChain next;
@ConditionalChain init(@Boolean cond, @ConditionalChain next) [
this::cond = cond;
this::next = next;
return this;
]
/*
* If the condition is true executes the closure and returns a false element, otherwise returns the next condition
*
* Execution starts from the first element, and iterates until the right element is found.
*/
@ConditionalChain then(@Closure<@Void> closure) [
if (isNull(next())) return new @ConditionalChain.init(false, null);
if (cond()) {
closure();
return new @ConditionalChain.init(false, null);
}
else return next();
]
/* Operators create a cool look */
@ConditionalChain operator then(@Closure<@Void> closure) alias @ConditionalChain.then;
@ConditionalChain operator else1(@Closure<@Void> closure) alias @ConditionalChain.then;
@ConditionalChain operator else2(@Closure<@Void> closure) alias @ConditionalChain.then;
@ConditionalChain operator orElse(@Closure<@Void> closure) alias @ConditionalChain.then;
};
/* Returns linked list [a && b, a, b, true] */
@ConditionalChain if2(@Boolean a, @Boolean b) [
return new @ConditionalChain.init(a && b, new @ConditionalChain.init(a, new @ConditionalChain.init(b, new @ConditionalChain.init(true, null))));
]
@Void main [
if2(false, true) then [
println("Not this!");
] else1 [
println("Not this!");
] else2 [
println("This!");
] orElse [
println("Not this!");
];
] |
http://rosettacode.org/wiki/FizzBuzz | FizzBuzz | Task
Write a program that prints the integers from 1 to 100 (inclusive).
But:
for multiples of three, print Fizz (instead of the number)
for multiples of five, print Buzz (instead of the number)
for multiples of both three and five, print FizzBuzz (instead of the number)
The FizzBuzz problem was presented as the lowest level of comprehension required to illustrate adequacy.
Also see
(a blog) dont-overthink-fizzbuzz
(a blog) fizzbuzz-the-programmers-stairway-to-heaven
| #Run_BASIC | Run BASIC | fn main() {
for i in 1..=100 {
match (i % 3, i % 5) {
(0, 0) => println!("fizzbuzz"),
(0, _) => println!("fizz"),
(_, 0) => println!("buzz"),
(_, _) => println!("{}", i),
}
}
} |
http://rosettacode.org/wiki/Extensible_prime_generator | Extensible prime generator | Task
Write a generator of prime numbers, in order, that will automatically adjust to accommodate the generation of any reasonably high prime.
The routine should demonstrably rely on either:
Being based on an open-ended counter set to count without upper limit other than system or programming language limits. In this case, explain where this counter is in the code.
Being based on a limit that is extended automatically. In this case, choose a small limit that ensures the limit will be passed when generating some of the values to be asked for below.
If other methods of creating an extensible prime generator are used, the algorithm's means of extensibility/lack of limits should be stated.
The routine should be used to:
Show the first twenty primes.
Show the primes between 100 and 150.
Show the number of primes between 7,700 and 8,000.
Show the 10,000th prime.
Show output on this page.
Note: You may reference code already on this site if it is written to be imported/included, then only the code necessary for import and the performance of this task need be shown. (It is also important to leave a forward link on the referenced tasks entry so that later editors know that the code is used for multiple tasks).
Note 2: If a languages in-built prime generator is extensible or is guaranteed to generate primes up to a system limit, (231 or memory overflow for example), then this may be used as long as an explanation of the limits of the prime generator is also given. (Which may include a link to/excerpt from, language documentation).
Note 3:The task is written so it may be useful in solving the task Emirp primes as well as others (depending on its efficiency).
Reference
Prime Numbers. Website with large count of primes.
| #Phix | Phix | with javascript_semantics
if platform()!=JS then free_console() end if
sequence primes = {2,3,5,7}
atom sieved = 10
procedure add_block()
integer N = min((sieved-1)*sieved,400000)
sequence sieve = repeat(1,N) -- sieve[i] is really i+sieved
for i=2 to length(primes) do -- (evens filtered on output)
atom p = primes[i], p2 = p*p
if p2>sieved+N then exit end if
if p2<sieved+1 then
p2 += ceil((sieved+1-p2)/p)*p
end if
p2 -= sieved
if and_bits(p2,1)=0 then p2 += p end if
-- if sieve[p2] then -- dang!
for k=p2 to N by p*2 do
sieve[k] = 0
end for
-- end if
end for
for i=1 to N by 2 do
if sieve[i] then
primes &= i+sieved
end if
end for
sieved += N
end procedure
function is_prime2(integer n)
while sieved<n do
add_block()
end while
return binary_search(n,primes)>0
end function
atom t0 = time()
while length(primes)<20 do add_block() end while
printf(1,"The first 20 primes are: ") ?primes[1..20]
while sieved<150 do add_block() end while
sequence s = {}
for k=abs(binary_search(100,primes)) to length(primes) do
integer p = primes[k]
if p>150 then exit end if
s &= p
end for
printf(1,"The primes between 100 and 150 are: ") ?s
s = {}
for i=7700 to 8000 do
if is_prime2(i) then s&=i end if
end for
printf(1,"There are %d primes between 7700 and 8000.\n",length(s))
for i=1 to iff(platform()=JS?7:8) do
integer k = power(10,i)
while length(primes)<k do
add_block()
end while
printf(1,"The %,dth prime is : %d\n",{k,primes[k]})
end for
?time()-t0
if platform()!=JS then {} = wait_key() end if
|
http://rosettacode.org/wiki/Execute_Brain**** | Execute Brain**** | Execute Brain**** is an implementation of Brainf***.
Other implementations of Brainf***.
RCBF is a set of Brainf*** compilers and interpreters written for Rosetta Code in a variety of languages.
Below are links to each of the versions of RCBF.
An implementation need only properly implement the following instructions:
Command
Description
>
Move the pointer to the right
<
Move the pointer to the left
+
Increment the memory cell under the pointer
-
Decrement the memory cell under the pointer
.
Output the character signified by the cell at the pointer
,
Input a character and store it in the cell at the pointer
[
Jump past the matching ] if the cell under the pointer is 0
]
Jump back to the matching [ if the cell under the pointer is nonzero
Any cell size is allowed, EOF (End-O-File) support is optional, as is whether you have bounded or unbounded memory.
| #AutoHotkey | AutoHotkey | ; AutoFucck
; A AutoIt Brainfuck Interpreter
; by minx
; AutoIt Version: 3.3.8.x
; Commands:
; - DEC
; + INC
; [ LOOP START
; ] LOOP END
; . Output cell value as ASCII Chr
; , Input a ASCII char (cell value = ASCII code)
; : Ouput cell value as integer
; ; Input a Integer
; _ Output a single whitespace
; / Output an Carriage Return and Line Feed
; You can load & save .atf Files.
#include <WindowsConstants.au3>
#include <EditConstants.au3>
#include <Array.au3>
#include <GUIConstants.au3>
#include <StaticCOnstants.au3>
HotKeySet("{F5}", "_Runn")
$hMain = GUICreate("Autofuck - Real Brainfuck Interpreter", 600, 525)
$mMain = GUICtrlCreateMenu("File")
Global $mCode = GUICtrlCreateMenu("Code")
$mInfo = GUICtrlCreateMenu("Info")
$mCredits = GUICtrlCreateMenuItem("Credits", $mInfo)
$mFile_New = GUICtrlCreateMenuItem("New", $mMain)
$mFile_Open = GUICtrlCreateMenuItem("Open", $mMain)
$mFile_Save = GUICtrlCreateMenuItem("Save", $mMain)
Global $mCode_Run = GUICtrlCreateMenuItem("Run [F5]", $mCode)
Global $lStatus = GUICtrlCreateLabel("++ Autofuck started...", 5, 480, 590, 20, $SS_SUNKEN)
GUICtrlSetFont(-1, Default, Default, Default, "Courier New")
$eCode = GUICtrlCreateEdit("", 5, 5, 590, 350)
GUICtrlSetFont(-1, Default, Default, Default, "Courier New")
$eConsole = GUICtrlCreateEdit("", 5, 360, 590, 115, $ES_WANTRETURN)
GUICtrlSetFont(-1, Default, Default, Default, "Courier New")
GUISetState()
While 1
$nMsg = GUIGetMsg()
Switch $nMsg
Case $mFile_New
GUICtrlSetData($eCode, "")
Case $mFile_Open
GUICtrlSetData($eCode, FileRead(FileOpenDialog("Open Autofuck script", @DesktopDir, "Autofuck (*.atf)")))
Case $mFile_Save
FileWrite(FileOpen(StringReplace(FileSaveDialog("Save Autofuck script", @DesktopDir, "Autofuck (*.atf)"), ".atf", "") &".atf", 2), GUICtrlRead($eCode))
Case $GUI_EVENT_CLOSE
Exit
Case $mCredits
MsgBox(0, "Autofuck", "Copyright by: "&@CRLF&"minx (autoit.de)"&@CRLF&"crashdemons (autoitscript.com)")
EndSwitch
WEnd
Func _Runn()
$Timer = TimerInit()
GUICtrlSetData($lStatus, "++ Program started")
Global $tData=DllStructCreate('BYTE[65536]')
Global $pData=0
GUICtrlSetData($eConsole, "")
Local $aError[6]=['','Unmatched closing bracket during search','Unmatched opening bracket during search','Unexpected closing bracket','Data pointer passed left boundary','Data pointer passed right boundary']
Local $sError=''
Local $i=_Run(GUICtrlRead($eCode))
If @error>=0 And @error<6 Then $sError=$aError[@error]
If StringLen($sError) Then GUICtrlSetData($eConsole, 'ERROR: '&$sError&'.'&@CRLF&'Ending Instruction Pointer: '&($i-1)&@CRLF&'Current Data Pointer: '&$pData)
GUICtrlSetData($lStatus, "++ Program terminated. Runtime: "& Round( TimerDiff($Timer) / 1000, 4) &"s")
EndFunc
Func _Run($Code,$iStart=1,$iEnd=0)
If $iEnd<1 Then $iEnd=StringLen($Code)
For $i = $iStart to $iEnd
Switch StringMid($Code, $i, 1)
Case ">"
$pData+=1
If $pData=65536 Then Return SetError(5,0,$i)
Case "<"
$pData-=1
If $pData<0 Then Return SetError(4,0,$i)
Case "+"
DllStructSetData($tData,1,DllStructGetData($tData,1,$pData+1)+1,$pData+1)
Case "-"
DllStructSetData($tData,1,DllStructGetData($tData,1,$pData+1)-1,$pData+1)
Case ":"
GUICtrlSetData($eConsole, GUICtrlRead($eConsole) & (DllStructGetData($tData,1,$pData+1)))
Case "."
GUICtrlSetData($eConsole, GUICtrlRead($eConsole) & Chr(DllStructGetData($tData,1,$pData+1)))
Case ";"
Local $cIn=StringMid(InputBox('Autofuck','Enter Number'),1)
DllStructSetData($tData,1,Number($cIn),$pData+1)
Case ","
Local $cIn=StringMid(InputBox('Autofuck','Enter one ASCII character'),1,1)
DllStructSetData($tData,1,Asc($cIn),$pData+1)
Case "["
Local $iStartSub=$i
Local $iEndSub=_MatchBracket($Code,$i,$iEnd)
If @error<>0 Then Return SetError(@error,0,$iEndSub)
While DllStructGetData($tData,1,$pData+1)<>0
Local $iRet=_Run($Code,$iStartSub+1,$iEndSub-1)
If @error<>0 Then Return SetError(@error,0,$iRet)
WEnd
$i=$iEndSub
Case ']'
Return SetError(3,0,$i)
Case "_"
GUICtrlSetData($eConsole, GUICtrlRead($eConsole)&" ")
Case "/"
GUICtrlSetData($eConsole, GUICtrlRead($eConsole)&@CRLF)
EndSwitch
Next
Return 0
EndFunc
Func _MatchBracket($Code,$iStart=1,$iEnd=0)
If $iEnd<1 Then $iEnd=StringLen($Code)
Local $Open=0
For $i=$iStart To $iEnd
Switch StringMid($Code,$i,1)
Case '['
$Open+=1
Case ']'
$Open-=1
If $Open=0 Then Return $i
If $Open<0 Then Return SetError(1,0,$i)
EndSwitch
Next
If $Open>0 Then Return SetError(2,0,$i)
Return 0
EndFunc |
http://rosettacode.org/wiki/Evolutionary_algorithm | Evolutionary algorithm | Starting with:
The target string: "METHINKS IT IS LIKE A WEASEL".
An array of random characters chosen from the set of upper-case letters together with the space, and of the same length as the target string. (Call it the parent).
A fitness function that computes the ‘closeness’ of its argument to the target string.
A mutate function that given a string and a mutation rate returns a copy of the string, with some characters probably mutated.
While the parent is not yet the target:
copy the parent C times, each time allowing some random probability that another character might be substituted using mutate.
Assess the fitness of the parent and all the copies to the target and make the most fit string the new parent, discarding the others.
repeat until the parent converges, (hopefully), to the target.
See also
Wikipedia entry: Weasel algorithm.
Wikipedia entry: Evolutionary algorithm.
Note: to aid comparison, try and ensure the variables and functions mentioned in the task description appear in solutions
A cursory examination of a few of the solutions reveals that the instructions have not been followed rigorously in some solutions. Specifically,
While the parent is not yet the target:
copy the parent C times, each time allowing some random probability that another character might be substituted using mutate.
Note that some of the the solutions given retain characters in the mutated string that are correct in the target string. However, the instruction above does not state to retain any of the characters while performing the mutation. Although some may believe to do so is implied from the use of "converges"
(:* repeat until the parent converges, (hopefully), to the target.
Strictly speaking, the new parent should be selected from the new pool of mutations, and then the new parent used to generate the next set of mutations with parent characters getting retained only by not being mutated. It then becomes possible that the new set of mutations has no member that is fitter than the parent!
As illustration of this error, the code for 8th has the following remark.
Create a new string based on the TOS, changing randomly any characters which
don't already match the target:
NOTE: this has been changed, the 8th version is completely random now
Clearly, this algo will be applying the mutation function only to the parent characters that don't match to the target characters!
To ensure that the new parent is never less fit than the prior parent, both the parent and all of the latest mutations are subjected to the fitness test to select the next parent.
| #AWK | AWK |
#!/bin/awk -f
function randchar(){
return substr(charset,randint(length(charset)+1),1)
}
function mutate(gene,rate ,l,newgene){
newgene = ""
for (l=1; l < 1+length(gene); l++){
if (rand() < rate)
newgene = newgene randchar()
else
newgene = newgene substr(gene,l,1)
}
return newgene
}
function fitness(gene,target ,k,fit){
fit = 0
for (k=1;k<1+length(gene);k++){
if (substr(gene,k,1) == substr(target,k,1)) fit = fit + 1
}
return fit
}
function randint(n){
return int(n * rand())
}
function evolve(){
maxfit = fitness(parent,target)
oldfit = maxfit
maxj = 0
for (j=1; j < D; j++){
child[j] = mutate(parent,mutrate)
fit[j] = fitness(child[j],target)
if (fit[j] > maxfit) {
maxfit = fit[j]
maxj = j
}
}
if (maxfit > oldfit) parent = child[maxj]
}
BEGIN{
target = "METHINKS IT IS LIKE A WEASEL"
charset = " ABCDEFGHIJKLMNOPQRSTUVWXYZ"
mutrate = 0.10
if (ARGC > 1) mutrate = ARGV[1]
lenset = length(charset)
C = 100
D = C + 1
parent = ""
for (j=1; j < length(target)+1; j++) {
parent = parent randchar()
}
print "target: " target
print "fitness of target: " fitness(target,target)
print "initial parent: " parent
gens = 0
while (parent != target){
evolve()
gens = gens + 1
if (gens % 10 == 0) print "after " gens " generations,","new parent: " parent," with fitness: " fitness(parent,target)
}
print "after " gens " generations,"," evolved parent: " parent
}
|
http://rosettacode.org/wiki/Fibonacci_sequence | Fibonacci sequence | The Fibonacci sequence is a sequence Fn of natural numbers defined recursively:
F0 = 0
F1 = 1
Fn = Fn-1 + Fn-2, if n>1
Task
Write a function to generate the nth Fibonacci number.
Solutions can be iterative or recursive (though recursive solutions are generally considered too slow and are mostly used as an exercise in recursion).
The sequence is sometimes extended into negative numbers by using a straightforward inverse of the positive definition:
Fn = Fn+2 - Fn+1, if n<0
support for negative n in the solution is optional.
Related tasks
Fibonacci n-step number sequences
Leonardo numbers
References
Wikipedia, Fibonacci number
Wikipedia, Lucas number
MathWorld, Fibonacci Number
Some identities for r-Fibonacci numbers
OEIS Fibonacci numbers
OEIS Lucas numbers
| #Kotlin | Kotlin | enum class Fibonacci {
ITERATIVE {
override fun get(n: Int): Long = if (n < 2) {
n.toLong()
} else {
var n1 = 0L
var n2 = 1L
repeat(n) {
val sum = n1 + n2
n1 = n2
n2 = sum
}
n1
}
},
RECURSIVE {
override fun get(n: Int): Long = if (n < 2) n.toLong() else this[n - 1] + this[n - 2]
},
CACHING {
val cache: MutableMap<Int, Long> = mutableMapOf(0 to 0L, 1 to 1L)
override fun get(n: Int): Long = if (n < 2) n.toLong() else impl(n)
private fun impl(n: Int): Long = cache.computeIfAbsent(n) { impl(it-1) + impl(it-2) }
},
;
abstract operator fun get(n: Int): Long
}
fun main() {
val r = 0..30
for (fib in Fibonacci.values()) {
print("${fib.name.padEnd(10)}:")
for (i in r) { print(" " + fib[i]) }
println()
}
} |
http://rosettacode.org/wiki/Factors_of_an_integer | Factors of an integer |
Basic Data Operation
This is a basic data operation. It represents a fundamental action on a basic data type.
You may see other such operations in the Basic Data Operations category, or:
Integer Operations
Arithmetic |
Comparison
Boolean Operations
Bitwise |
Logical
String Operations
Concatenation |
Interpolation |
Comparison |
Matching
Memory Operations
Pointers & references |
Addresses
Task
Compute the factors of a positive integer.
These factors are the positive integers by which the number being factored can be divided to yield a positive integer result.
(Though the concepts function correctly for zero and negative integers, the set of factors of zero has countably infinite members, and the factors of negative integers can be obtained from the factors of related positive numbers without difficulty; this task does not require handling of either of these cases).
Note that every prime number has two factors: 1 and itself.
Related tasks
count in factors
prime decomposition
Sieve of Eratosthenes
primality by trial division
factors of a Mersenne number
trial factoring of a Mersenne number
partition an integer X into N primes
sequence of primes by Trial Division
sequence: smallest number greater than previous term with exactly n divisors
| #UNIX_Shell | UNIX Shell | factor() {
r=`echo "sqrt($1)" | bc` # or `echo $1 v p | dc`
i=1
while [ $i -lt $r ]; do
if [ `expr $1 % $i` -eq 0 ]; then
echo $i
expr $1 / $i
fi
i=`expr $i + 1`
done | sort -nu
}
|
http://rosettacode.org/wiki/Factors_of_an_integer | Factors of an integer |
Basic Data Operation
This is a basic data operation. It represents a fundamental action on a basic data type.
You may see other such operations in the Basic Data Operations category, or:
Integer Operations
Arithmetic |
Comparison
Boolean Operations
Bitwise |
Logical
String Operations
Concatenation |
Interpolation |
Comparison |
Matching
Memory Operations
Pointers & references |
Addresses
Task
Compute the factors of a positive integer.
These factors are the positive integers by which the number being factored can be divided to yield a positive integer result.
(Though the concepts function correctly for zero and negative integers, the set of factors of zero has countably infinite members, and the factors of negative integers can be obtained from the factors of related positive numbers without difficulty; this task does not require handling of either of these cases).
Note that every prime number has two factors: 1 and itself.
Related tasks
count in factors
prime decomposition
Sieve of Eratosthenes
primality by trial division
factors of a Mersenne number
trial factoring of a Mersenne number
partition an integer X into N primes
sequence of primes by Trial Division
sequence: smallest number greater than previous term with exactly n divisors
| #Ursa | Ursa | decl int n
set n (int args<1>)
decl int i
for (set i 1) (< i (+ (/ n 2) 1)) (inc i)
if (= (mod n i) 0)
out i " " console
end if
end for
out n endl console |
http://rosettacode.org/wiki/Execute_HQ9%2B | Execute HQ9+ | Task
Implement a HQ9+ interpreter or compiler.
| #Julia | Julia | hello() = println("Hello, world!")
quine() = println(src)
bottles() = for i = 99:-1:1 print("\n$i bottles of beer on the wall\n$i bottles of beer\nTake one down, pass it around\n$(i-1) bottles of beer on the wall\n") end
acc = 0
incr() = global acc += 1
const dispatch = Dict(
'h' => hello,
'q' => quine,
'9' => bottles,
'+' => incr)
if length(ARGS) < 1
println("Usage: julia ./HQ9+.jl file.hq9")
exit(1)
else
file = ARGS[1]
end
try
open(file) do s
global src = readstring(s)
end
catch
warning("can't open $file")
exit(1)
end
for i in lowercase(src)
if haskey(dispatch, i) dispatch[i]() end
end |
http://rosettacode.org/wiki/Execute_HQ9%2B | Execute HQ9+ | Task
Implement a HQ9+ interpreter or compiler.
| #Kotlin | Kotlin | // version 1.1.3
fun hq9plus(code: String) {
var acc = 0
val sb = StringBuilder()
for (c in code) {
sb.append(
when (c) {
'h', 'H' -> "Hello, world!\n"
'q', 'Q' -> code + "\n"
'9'-> {
val sb2 = StringBuilder()
for (i in 99 downTo 1) {
val s = if (i > 1) "s" else ""
sb2.append("$i bottle$s of beer on the wall\n")
sb2.append("$i bottle$s of beer\n")
sb2.append("Take one down, pass it around\n")
}
sb2.append("No more bottles of beer on the wall!\n")
sb2.toString()
}
'+' -> { acc++; "" } // yeah, it's weird!
else -> throw IllegalArgumentException("Code contains illegal operation '$c'")
}
)
}
println(sb)
}
fun main(args: Array<String>) {
val code = args[0] // pass in code as command line argument (using hq9+)
hq9plus(code)
} |
http://rosettacode.org/wiki/Execute_a_Markov_algorithm | Execute a Markov algorithm | Execute a Markov algorithm
You are encouraged to solve this task according to the task description, using any language you may know.
Task
Create an interpreter for a Markov Algorithm.
Rules have the syntax:
<ruleset> ::= ((<comment> | <rule>) <newline>+)*
<comment> ::= # {<any character>}
<rule> ::= <pattern> <whitespace> -> <whitespace> [.] <replacement>
<whitespace> ::= (<tab> | <space>) [<whitespace>]
There is one rule per line.
If there is a . (period) present before the <replacement>, then this is a terminating rule in which case the interpreter must halt execution.
A ruleset consists of a sequence of rules, with optional comments.
Rulesets
Use the following tests on entries:
Ruleset 1
# This rules file is extracted from Wikipedia:
# http://en.wikipedia.org/wiki/Markov_Algorithm
A -> apple
B -> bag
S -> shop
T -> the
the shop -> my brother
a never used -> .terminating rule
Sample text of:
I bought a B of As from T S.
Should generate the output:
I bought a bag of apples from my brother.
Ruleset 2
A test of the terminating rule
# Slightly modified from the rules on Wikipedia
A -> apple
B -> bag
S -> .shop
T -> the
the shop -> my brother
a never used -> .terminating rule
Sample text of:
I bought a B of As from T S.
Should generate:
I bought a bag of apples from T shop.
Ruleset 3
This tests for correct substitution order and may trap simple regexp based replacement routines if special regexp characters are not escaped.
# BNF Syntax testing rules
A -> apple
WWWW -> with
Bgage -> ->.*
B -> bag
->.* -> money
W -> WW
S -> .shop
T -> the
the shop -> my brother
a never used -> .terminating rule
Sample text of:
I bought a B of As W my Bgage from T S.
Should generate:
I bought a bag of apples with my money from T shop.
Ruleset 4
This tests for correct order of scanning of rules, and may trap replacement routines that scan in the wrong order. It implements a general unary multiplication engine. (Note that the input expression must be placed within underscores in this implementation.)
### Unary Multiplication Engine, for testing Markov Algorithm implementations
### By Donal Fellows.
# Unary addition engine
_+1 -> _1+
1+1 -> 11+
# Pass for converting from the splitting of multiplication into ordinary
# addition
1! -> !1
,! -> !+
_! -> _
# Unary multiplication by duplicating left side, right side times
1*1 -> x,@y
1x -> xX
X, -> 1,1
X1 -> 1X
_x -> _X
,x -> ,X
y1 -> 1y
y_ -> _
# Next phase of applying
1@1 -> x,@y
1@_ -> @_
,@_ -> !_
++ -> +
# Termination cleanup for addition
_1 -> 1
1+_ -> 1
_+_ ->
Sample text of:
_1111*11111_
should generate the output:
11111111111111111111
Ruleset 5
A simple Turing machine,
implementing a three-state busy beaver.
The tape consists of 0s and 1s, the states are A, B, C and H (for Halt), and the head position is indicated by writing the state letter before the character where the head is.
All parts of the initial tape the machine operates on have to be given in the input.
Besides demonstrating that the Markov algorithm is Turing-complete, it also made me catch a bug in the C++ implementation which wasn't caught by the first four rulesets.
# Turing machine: three-state busy beaver
#
# state A, symbol 0 => write 1, move right, new state B
A0 -> 1B
# state A, symbol 1 => write 1, move left, new state C
0A1 -> C01
1A1 -> C11
# state B, symbol 0 => write 1, move left, new state A
0B0 -> A01
1B0 -> A11
# state B, symbol 1 => write 1, move right, new state B
B1 -> 1B
# state C, symbol 0 => write 1, move left, new state B
0C0 -> B01
1C0 -> B11
# state C, symbol 1 => write 1, move left, halt
0C1 -> H01
1C1 -> H11
This ruleset should turn
000000A000000
into
00011H1111000
| #Icon_and_Unicon | Icon and Unicon | procedure main(A)
rules := loadRules(open(A[1],"r"))
every write(line := !&input, " -> ",apply(rules, line))
end
record rule(pat, term, rep)
procedure loadRules(f)
rules := []
every !f ? if not ="#" then put(rules,
rule(1(trim(tab(find("->"))),move(2),tab(many(' \t'))),
(="."|&null), trim(tab(0))))
return rules
end
procedure apply(rules, line)
s := line
repeat {
s ?:= tab(find((r := !rules).pat)) || r.rep || (move(*r.pat),tab(0))
if (s == line) | \r.term then return s else line := s
}
end |
http://rosettacode.org/wiki/Exceptions/Catch_an_exception_thrown_in_a_nested_call | Exceptions/Catch an exception thrown in a nested call | Show how to create a user-defined exception and show how to catch an exception raised from several nested calls away.
Create two user-defined exceptions, U0 and U1.
Have function foo call function bar twice.
Have function bar call function baz.
Arrange for function baz to raise, or throw exception U0 on its first call, then exception U1 on its second.
Function foo should catch only exception U0, not U1.
Show/describe what happens when the program is run.
| #Java | Java | class U0 extends Exception { }
class U1 extends Exception { }
public class ExceptionsTest {
public static void foo() throws U1 {
for (int i = 0; i <= 1; i++) {
try {
bar(i);
} catch (U0 e) {
System.out.println("Function foo caught exception U0");
}
}
}
public static void bar(int i) throws U0, U1 {
baz(i); // Nest those calls
}
public static void baz(int i) throws U0, U1 {
if (i == 0)
throw new U0();
else
throw new U1();
}
public static void main(String[] args) throws U1 {
foo();
}
} |
http://rosettacode.org/wiki/Exceptions/Catch_an_exception_thrown_in_a_nested_call | Exceptions/Catch an exception thrown in a nested call | Show how to create a user-defined exception and show how to catch an exception raised from several nested calls away.
Create two user-defined exceptions, U0 and U1.
Have function foo call function bar twice.
Have function bar call function baz.
Arrange for function baz to raise, or throw exception U0 on its first call, then exception U1 on its second.
Function foo should catch only exception U0, not U1.
Show/describe what happens when the program is run.
| #JavaScript | JavaScript | function U() {}
U.prototype.toString = function(){return this.className;}
function U0() {
this.className = arguments.callee.name;
}
U0.prototype = new U();
function U1() {
this.className = arguments.callee.name;
}
U1.prototype = new U();
function foo() {
for (var i = 1; i <= 2; i++) {
try {
bar();
}
catch(e if e instanceof U0) {
print("caught exception " + e);
}
}
}
function bar() {
baz();
}
function baz() {
// during the first call, redefine the function for subsequent calls
baz = function() {throw(new U1());}
throw(new U0());
}
foo(); |
http://rosettacode.org/wiki/Exceptions | Exceptions | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
This task is to give an example of an exception handling routine
and to "throw" a new exception.
Related task
Exceptions Through Nested Calls
| #Fancy | Fancy | # define custom exception class
# StandardError is base class for all exception classes
class MyError : StandardError {
def initialize: message {
# forward to StdError's initialize method
super initialize: message
}
}
try {
# raises/throws a new MyError exception within try-block
MyError new: "my message" . raise!
} catch MyError => e {
# catch exception
# this will print "my message"
e message println
} finally {
# this will always be executed (as in e.g. Java)
"This is how exception handling in Fancy works :)" println
} |
http://rosettacode.org/wiki/Exceptions | Exceptions | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
This task is to give an example of an exception handling routine
and to "throw" a new exception.
Related task
Exceptions Through Nested Calls
| #Fantom | Fantom |
// Create a new error class by subclassing sys::Err
const class SpecialErr : Err
{
// you must provide some message about the error
// to the parent class, for reporting
new make () : super ("special error") {}
}
class Main
{
static Void fn ()
{
throw SpecialErr ()
}
public static Void main ()
{
try
fn()
catch (SpecialErr e)
echo ("Caught " + e)
}
}
|
http://rosettacode.org/wiki/Execute_a_system_command | Execute a system command | Task
Run either the ls system command (dir on Windows), or the pause system command.
Related task
Get system command output
| #D | D |
import std.process, std.stdio;
//these two alternatives wait for the process to return, and capture the output
//each process function returns a Tuple of (int)"status" and (string)"output
auto ls_string = executeShell("ls -l"); //takes single string
writeln((ls_string.status == 0) ? ls_string.output : "command failed");
auto ls_array = execute(["ls", "-l"]); //takes array of strings
writeln((ls_array.status == 0) ? ls_array.output : "command failed");
//other alternatives exist to spawn processes in parallel and capture output via pipes
|
http://rosettacode.org/wiki/Execute_a_system_command | Execute a system command | Task
Run either the ls system command (dir on Windows), or the pause system command.
Related task
Get system command output
| #dc | dc | ! ls |
http://rosettacode.org/wiki/Factorial | Factorial | Definitions
The factorial of 0 (zero) is defined as being 1 (unity).
The Factorial Function of a positive integer, n, is defined as the product of the sequence:
n, n-1, n-2, ... 1
Task
Write a function to return the factorial of a number.
Solutions can be iterative or recursive.
Support for trapping negative n errors is optional.
Related task
Primorial numbers
| #AppleScript | AppleScript | on factorial(x)
if x < 0 then return 0
set R to 1
repeat while x > 1
set {R, x} to {R * x, x - 1}
end repeat
return R
end factorial |
http://rosettacode.org/wiki/Exponentiation_operator | Exponentiation operator | Most programming languages have a built-in implementation of exponentiation.
Task
Re-implement integer exponentiation for both intint and floatint as both a procedure, and an operator (if your language supports operator definition).
If the language supports operator (or procedure) overloading, then an overloaded form should be provided for both intint and floatint variants.
Related tasks
Exponentiation order
arbitrary-precision integers (included)
Exponentiation with infix operators in (or operating on) the base
| #Julia | Julia |
function pow(base::Number, exp::Integer)
r = one(base)
for i = 1:exp
r *= base
end
return r
end
|
http://rosettacode.org/wiki/Exponentiation_operator | Exponentiation operator | Most programming languages have a built-in implementation of exponentiation.
Task
Re-implement integer exponentiation for both intint and floatint as both a procedure, and an operator (if your language supports operator definition).
If the language supports operator (or procedure) overloading, then an overloaded form should be provided for both intint and floatint variants.
Related tasks
Exponentiation order
arbitrary-precision integers (included)
Exponentiation with infix operators in (or operating on) the base
| #Kotlin | Kotlin | // version 1.0.6
infix fun Int.ipow(exp: Int): Int =
when {
this == 1 -> 1
this == -1 -> if (exp and 1 == 0) 1 else -1
exp < 0 -> throw IllegalArgumentException("invalid exponent")
exp == 0 -> 1
else -> {
var ans = 1
var base = this
var e = exp
while (e > 1) {
if (e and 1 == 1) ans *= base
e = e shr 1
base *= base
}
ans * base
}
}
infix fun Double.dpow(exp: Int): Double {
var ans = 1.0
var e = exp
var base = if (e < 0) 1.0 / this else this
if (e < 0) e = -e
while (e > 0) {
if (e and 1 == 1) ans *= base
e = e shr 1
base *= base
}
return ans
}
fun main(args: Array<String>) {
println("2 ^ 3 = ${2 ipow 3}")
println("1 ^ -10 = ${1 ipow -10}")
println("-1 ^ -3 = ${-1 ipow -3}")
println()
println("2.0 ^ -3 = ${2.0 dpow -3}")
println("1.5 ^ 0 = ${1.5 dpow 0}")
println("4.5 ^ 2 = ${4.5 dpow 2}")
} |
http://rosettacode.org/wiki/Extend_your_language | Extend your language | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
Some programming languages allow you to extend the language. While this can be done to a certain degree in most languages (e.g. by using macros), other languages go much further. Most notably in the Forth and Lisp families, programming per se is done by extending the language without any formal distinction between built-in and user-defined elements.
If your language supports it, show how to introduce a new flow control mechanism. A practical and useful example is a four-way branch:
Occasionally, code must be written that depends on two conditions, resulting in up to four branches (depending on whether both, only the first, only the second, or none of the conditions are "true"). In a C-like language this could look like the following:
if (condition1isTrue) {
if (condition2isTrue)
bothConditionsAreTrue();
else
firstConditionIsTrue();
}
else if (condition2isTrue)
secondConditionIsTrue();
else
noConditionIsTrue();
Besides being rather cluttered, the statement(s) for 'condition2isTrue' must be written down twice. If 'condition2isTrue' were a lengthy and involved expression, it would be quite unreadable, and the code generated by the compiler might be unnecessarily large.
This can be improved by introducing a new keyword if2. It is similar to if, but takes two conditional statements instead of one, and up to three 'else' statements. One proposal (in pseudo-C syntax) might be:
if2 (condition1isTrue) (condition2isTrue)
bothConditionsAreTrue();
else1
firstConditionIsTrue();
else2
secondConditionIsTrue();
else
noConditionIsTrue();
Pick the syntax which suits your language. The keywords 'else1' and 'else2' are just examples. The new conditional expression should look, nest and behave analogously to the language's built-in 'if' statement.
| #PicoLisp | PicoLisp | (undef 'if2) # Undefine the built-in 'if2'
(de if2 "P"
(if (eval (pop '"P"))
(eval ((if (eval (car "P")) cadr caddr) "P"))
(if (eval (car "P"))
(eval (cadddr "P"))
(run (cddddr "P")) ) ) ) |
http://rosettacode.org/wiki/Extend_your_language | Extend your language | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
Some programming languages allow you to extend the language. While this can be done to a certain degree in most languages (e.g. by using macros), other languages go much further. Most notably in the Forth and Lisp families, programming per se is done by extending the language without any formal distinction between built-in and user-defined elements.
If your language supports it, show how to introduce a new flow control mechanism. A practical and useful example is a four-way branch:
Occasionally, code must be written that depends on two conditions, resulting in up to four branches (depending on whether both, only the first, only the second, or none of the conditions are "true"). In a C-like language this could look like the following:
if (condition1isTrue) {
if (condition2isTrue)
bothConditionsAreTrue();
else
firstConditionIsTrue();
}
else if (condition2isTrue)
secondConditionIsTrue();
else
noConditionIsTrue();
Besides being rather cluttered, the statement(s) for 'condition2isTrue' must be written down twice. If 'condition2isTrue' were a lengthy and involved expression, it would be quite unreadable, and the code generated by the compiler might be unnecessarily large.
This can be improved by introducing a new keyword if2. It is similar to if, but takes two conditional statements instead of one, and up to three 'else' statements. One proposal (in pseudo-C syntax) might be:
if2 (condition1isTrue) (condition2isTrue)
bothConditionsAreTrue();
else1
firstConditionIsTrue();
else2
secondConditionIsTrue();
else
noConditionIsTrue();
Pick the syntax which suits your language. The keywords 'else1' and 'else2' are just examples. The new conditional expression should look, nest and behave analogously to the language's built-in 'if' statement.
| #Plain_TeX | Plain TeX | \def\iftwo#1#2#3#4#5\elsefirst#6\elsesecond#7\elseneither#8\owtfi
{\if#1#2\if#3#4#5\else#6\fi\else\if#3#4#7\else#8\fi\fi}
\def\both{***both***}
\def\first{***first***}
\def\second{***second***}
\def\neither{***neither***}
\message{\iftwo{1}{1}{2}{2}\both\elsefirst\first\elsesecond\second\elseneither\neither\owtfi}
\message{\iftwo{1}{1}{2}{-2}\both\elsefirst\first\elsesecond\second\elseneither\neither\owtfi}
\message{\iftwo{1}{-1}{2}{2}\both\elsefirst\first\elsesecond\second\elseneither\neither\owtfi}
\message{\iftwo{1}{-1}{2}{-2}\both\elsefirst\first\elsesecond\second\elseneither\neither\owtfi}
\bye |
http://rosettacode.org/wiki/FizzBuzz | FizzBuzz | Task
Write a program that prints the integers from 1 to 100 (inclusive).
But:
for multiples of three, print Fizz (instead of the number)
for multiples of five, print Buzz (instead of the number)
for multiples of both three and five, print FizzBuzz (instead of the number)
The FizzBuzz problem was presented as the lowest level of comprehension required to illustrate adequacy.
Also see
(a blog) dont-overthink-fizzbuzz
(a blog) fizzbuzz-the-programmers-stairway-to-heaven
| #Rust | Rust | fn main() {
for i in 1..=100 {
match (i % 3, i % 5) {
(0, 0) => println!("fizzbuzz"),
(0, _) => println!("fizz"),
(_, 0) => println!("buzz"),
(_, _) => println!("{}", i),
}
}
} |
http://rosettacode.org/wiki/Extensible_prime_generator | Extensible prime generator | Task
Write a generator of prime numbers, in order, that will automatically adjust to accommodate the generation of any reasonably high prime.
The routine should demonstrably rely on either:
Being based on an open-ended counter set to count without upper limit other than system or programming language limits. In this case, explain where this counter is in the code.
Being based on a limit that is extended automatically. In this case, choose a small limit that ensures the limit will be passed when generating some of the values to be asked for below.
If other methods of creating an extensible prime generator are used, the algorithm's means of extensibility/lack of limits should be stated.
The routine should be used to:
Show the first twenty primes.
Show the primes between 100 and 150.
Show the number of primes between 7,700 and 8,000.
Show the 10,000th prime.
Show output on this page.
Note: You may reference code already on this site if it is written to be imported/included, then only the code necessary for import and the performance of this task need be shown. (It is also important to leave a forward link on the referenced tasks entry so that later editors know that the code is used for multiple tasks).
Note 2: If a languages in-built prime generator is extensible or is guaranteed to generate primes up to a system limit, (231 or memory overflow for example), then this may be used as long as an explanation of the limits of the prime generator is also given. (Which may include a link to/excerpt from, language documentation).
Note 3:The task is written so it may be useful in solving the task Emirp primes as well as others (depending on its efficiency).
Reference
Prime Numbers. Website with large count of primes.
| #PicoLisp | PicoLisp | (de prime? (N Lst)
(let S (sqrt N)
(for D Lst
(T (> D S) T)
(T (=0 (% N D)) NIL) ) ) )
(de primeseq (A B)
(let (I 1 R)
(nth
(make
(link 2)
(while (> A (inc 'I 2))
(and (prime? I (made)) (link I)) )
(setq R (length (made)))
(while (> B I)
(and (prime? I (made)) (link I))
(inc 'I 2) ) )
(inc R) ) ) )
(de take (N)
(let I 1
(make
(link 2)
(do (dec N)
(until (prime? (inc 'I 2) (made)))
(link I) ) ) ) )
(prin "First 20 primes: ")
(println (take 20))
(prin "Primes between 100 and 150: ")
(println (primeseq 100 150))
(prinl
"Number of primes between 7700 and 8000: "
(length (primeseq 7700 8000)) )
(for N (10 100 1000 10000 100000 1000000)
(prinl
N
"th prime: "
(last (take N)) ) ) |
http://rosettacode.org/wiki/Execute_Brain**** | Execute Brain**** | Execute Brain**** is an implementation of Brainf***.
Other implementations of Brainf***.
RCBF is a set of Brainf*** compilers and interpreters written for Rosetta Code in a variety of languages.
Below are links to each of the versions of RCBF.
An implementation need only properly implement the following instructions:
Command
Description
>
Move the pointer to the right
<
Move the pointer to the left
+
Increment the memory cell under the pointer
-
Decrement the memory cell under the pointer
.
Output the character signified by the cell at the pointer
,
Input a character and store it in the cell at the pointer
[
Jump past the matching ] if the cell under the pointer is 0
]
Jump back to the matching [ if the cell under the pointer is nonzero
Any cell size is allowed, EOF (End-O-File) support is optional, as is whether you have bounded or unbounded memory.
| #AutoIt | AutoIt | ; AutoFucck
; A AutoIt Brainfuck Interpreter
; by minx
; AutoIt Version: 3.3.8.x
; Commands:
; - DEC
; + INC
; [ LOOP START
; ] LOOP END
; . Output cell value as ASCII Chr
; , Input a ASCII char (cell value = ASCII code)
; : Ouput cell value as integer
; ; Input a Integer
; _ Output a single whitespace
; / Output an Carriage Return and Line Feed
; You can load & save .atf Files.
#include <WindowsConstants.au3>
#include <EditConstants.au3>
#include <Array.au3>
#include <GUIConstants.au3>
#include <StaticCOnstants.au3>
HotKeySet("{F5}", "_Runn")
$hMain = GUICreate("Autofuck - Real Brainfuck Interpreter", 600, 525)
$mMain = GUICtrlCreateMenu("File")
Global $mCode = GUICtrlCreateMenu("Code")
$mInfo = GUICtrlCreateMenu("Info")
$mCredits = GUICtrlCreateMenuItem("Credits", $mInfo)
$mFile_New = GUICtrlCreateMenuItem("New", $mMain)
$mFile_Open = GUICtrlCreateMenuItem("Open", $mMain)
$mFile_Save = GUICtrlCreateMenuItem("Save", $mMain)
Global $mCode_Run = GUICtrlCreateMenuItem("Run [F5]", $mCode)
Global $lStatus = GUICtrlCreateLabel("++ Autofuck started...", 5, 480, 590, 20, $SS_SUNKEN)
GUICtrlSetFont(-1, Default, Default, Default, "Courier New")
$eCode = GUICtrlCreateEdit("", 5, 5, 590, 350)
GUICtrlSetFont(-1, Default, Default, Default, "Courier New")
$eConsole = GUICtrlCreateEdit("", 5, 360, 590, 115, $ES_WANTRETURN)
GUICtrlSetFont(-1, Default, Default, Default, "Courier New")
GUISetState()
While 1
$nMsg = GUIGetMsg()
Switch $nMsg
Case $mFile_New
GUICtrlSetData($eCode, "")
Case $mFile_Open
GUICtrlSetData($eCode, FileRead(FileOpenDialog("Open Autofuck script", @DesktopDir, "Autofuck (*.atf)")))
Case $mFile_Save
FileWrite(FileOpen(StringReplace(FileSaveDialog("Save Autofuck script", @DesktopDir, "Autofuck (*.atf)"), ".atf", "") &".atf", 2), GUICtrlRead($eCode))
Case $GUI_EVENT_CLOSE
Exit
Case $mCredits
MsgBox(0, "Autofuck", "Copyright by: "&@CRLF&"minx (autoit.de)"&@CRLF&"crashdemons (autoitscript.com)")
EndSwitch
WEnd
Func _Runn()
$Timer = TimerInit()
GUICtrlSetData($lStatus, "++ Program started")
Global $tData=DllStructCreate('BYTE[65536]')
Global $pData=0
GUICtrlSetData($eConsole, "")
Local $aError[6]=['','Unmatched closing bracket during search','Unmatched opening bracket during search','Unexpected closing bracket','Data pointer passed left boundary','Data pointer passed right boundary']
Local $sError=''
Local $i=_Run(GUICtrlRead($eCode))
If @error>=0 And @error<6 Then $sError=$aError[@error]
If StringLen($sError) Then GUICtrlSetData($eConsole, 'ERROR: '&$sError&'.'&@CRLF&'Ending Instruction Pointer: '&($i-1)&@CRLF&'Current Data Pointer: '&$pData)
GUICtrlSetData($lStatus, "++ Program terminated. Runtime: "& Round( TimerDiff($Timer) / 1000, 4) &"s")
EndFunc
Func _Run($Code,$iStart=1,$iEnd=0)
If $iEnd<1 Then $iEnd=StringLen($Code)
For $i = $iStart to $iEnd
Switch StringMid($Code, $i, 1)
Case ">"
$pData+=1
If $pData=65536 Then Return SetError(5,0,$i)
Case "<"
$pData-=1
If $pData<0 Then Return SetError(4,0,$i)
Case "+"
DllStructSetData($tData,1,DllStructGetData($tData,1,$pData+1)+1,$pData+1)
Case "-"
DllStructSetData($tData,1,DllStructGetData($tData,1,$pData+1)-1,$pData+1)
Case ":"
GUICtrlSetData($eConsole, GUICtrlRead($eConsole) & (DllStructGetData($tData,1,$pData+1)))
Case "."
GUICtrlSetData($eConsole, GUICtrlRead($eConsole) & Chr(DllStructGetData($tData,1,$pData+1)))
Case ";"
Local $cIn=StringMid(InputBox('Autofuck','Enter Number'),1)
DllStructSetData($tData,1,Number($cIn),$pData+1)
Case ","
Local $cIn=StringMid(InputBox('Autofuck','Enter one ASCII character'),1,1)
DllStructSetData($tData,1,Asc($cIn),$pData+1)
Case "["
Local $iStartSub=$i
Local $iEndSub=_MatchBracket($Code,$i,$iEnd)
If @error<>0 Then Return SetError(@error,0,$iEndSub)
While DllStructGetData($tData,1,$pData+1)<>0
Local $iRet=_Run($Code,$iStartSub+1,$iEndSub-1)
If @error<>0 Then Return SetError(@error,0,$iRet)
WEnd
$i=$iEndSub
Case ']'
Return SetError(3,0,$i)
Case "_"
GUICtrlSetData($eConsole, GUICtrlRead($eConsole)&" ")
Case "/"
GUICtrlSetData($eConsole, GUICtrlRead($eConsole)&@CRLF)
EndSwitch
Next
Return 0
EndFunc
Func _MatchBracket($Code,$iStart=1,$iEnd=0)
If $iEnd<1 Then $iEnd=StringLen($Code)
Local $Open=0
For $i=$iStart To $iEnd
Switch StringMid($Code,$i,1)
Case '['
$Open+=1
Case ']'
$Open-=1
If $Open=0 Then Return $i
If $Open<0 Then Return SetError(1,0,$i)
EndSwitch
Next
If $Open>0 Then Return SetError(2,0,$i)
Return 0
EndFunc |
http://rosettacode.org/wiki/Evolutionary_algorithm | Evolutionary algorithm | Starting with:
The target string: "METHINKS IT IS LIKE A WEASEL".
An array of random characters chosen from the set of upper-case letters together with the space, and of the same length as the target string. (Call it the parent).
A fitness function that computes the ‘closeness’ of its argument to the target string.
A mutate function that given a string and a mutation rate returns a copy of the string, with some characters probably mutated.
While the parent is not yet the target:
copy the parent C times, each time allowing some random probability that another character might be substituted using mutate.
Assess the fitness of the parent and all the copies to the target and make the most fit string the new parent, discarding the others.
repeat until the parent converges, (hopefully), to the target.
See also
Wikipedia entry: Weasel algorithm.
Wikipedia entry: Evolutionary algorithm.
Note: to aid comparison, try and ensure the variables and functions mentioned in the task description appear in solutions
A cursory examination of a few of the solutions reveals that the instructions have not been followed rigorously in some solutions. Specifically,
While the parent is not yet the target:
copy the parent C times, each time allowing some random probability that another character might be substituted using mutate.
Note that some of the the solutions given retain characters in the mutated string that are correct in the target string. However, the instruction above does not state to retain any of the characters while performing the mutation. Although some may believe to do so is implied from the use of "converges"
(:* repeat until the parent converges, (hopefully), to the target.
Strictly speaking, the new parent should be selected from the new pool of mutations, and then the new parent used to generate the next set of mutations with parent characters getting retained only by not being mutated. It then becomes possible that the new set of mutations has no member that is fitter than the parent!
As illustration of this error, the code for 8th has the following remark.
Create a new string based on the TOS, changing randomly any characters which
don't already match the target:
NOTE: this has been changed, the 8th version is completely random now
Clearly, this algo will be applying the mutation function only to the parent characters that don't match to the target characters!
To ensure that the new parent is never less fit than the prior parent, both the parent and all of the latest mutations are subjected to the fitness test to select the next parent.
| #Batch_File | Batch File |
@echo off
setlocal enabledelayedexpansion
set target=M E T H I N K S @ I T @ I S @ L I K E @ A @ W E A S E L
set chars=A B C D E F G H I J K L M N O P Q R S T U V W X Y Z @
set tempcount=0
for %%i in (%target%) do (
set /a tempcount+=1
set target!tempcount!=%%i
)
call:parent
echo %target%
echo --------------------------------------------------------
:loop
call:fitness parent
set currentfit=%errorlevel%
if %currentfit%==28 goto end
echo %parent% - %currentfit% [%attempts%]
set attempts=0
:innerloop
set /a attempts+=1
title Attemps - %attempts%
call:mutate %parent%
call:fitness tempparent
set newfit=%errorlevel%
if %newfit% gtr %currentfit% (
set tempcount=0
set "parent="
for %%i in (%tempparent%) do (
set /a tempcount+=1
set parent!tempcount!=%%i
set parent=!parent! %%i
)
goto loop
)
goto innerloop
:end
echo %parent% - %currentfit% [%attempts%]
echo Done.
exit /b
:parent
set "parent="
for /l %%i in (1,1,28) do (
set /a charchosen=!random! %% 27 + 1
set tempcount=0
for %%j in (%chars%) do (
set /a tempcount+=1
if !charchosen!==!tempcount! (
set parent%%i=%%j
set parent=!parent! %%j
)
)
)
exit /b
:fitness
set fitness=0
set array=%1
for /l %%i in (1,1,28) do if !%array%%%i!==!target%%i! set /a fitness+=1
exit /b %fitness%
:mutate
set tempcount=0
set returnarray=tempparent
set "%returnarray%="
for %%i in (%*) do (
set /a tempcount+=1
set %returnarray%!tempcount!=%%i
set %returnarray%=!%returnarray%! %%i
)
set /a tomutate=%random% %% 28 + 1
set /a mutateto=%random% %% 27 + 1
set tempcount=0
for %%i in (%chars%) do (
set /a tempcount+=1
if %mutateto%==!tempcount! (
set %returnarray%!tomutate!=%%i
)
)
set "%returnarray%="
for /l %%i in (1,1,28) do set %returnarray%=!%returnarray%! !%returnarray%%%i!
exit /b
|
http://rosettacode.org/wiki/Fibonacci_sequence | Fibonacci sequence | The Fibonacci sequence is a sequence Fn of natural numbers defined recursively:
F0 = 0
F1 = 1
Fn = Fn-1 + Fn-2, if n>1
Task
Write a function to generate the nth Fibonacci number.
Solutions can be iterative or recursive (though recursive solutions are generally considered too slow and are mostly used as an exercise in recursion).
The sequence is sometimes extended into negative numbers by using a straightforward inverse of the positive definition:
Fn = Fn+2 - Fn+1, if n<0
support for negative n in the solution is optional.
Related tasks
Fibonacci n-step number sequences
Leonardo numbers
References
Wikipedia, Fibonacci number
Wikipedia, Lucas number
MathWorld, Fibonacci Number
Some identities for r-Fibonacci numbers
OEIS Fibonacci numbers
OEIS Lucas numbers
| #L.2B.2B | L++ | (defn int fib (int n) (return (? (< n 2) n (+ (fib (- n 1)) (fib (- n 2))))))
(main (prn (fib 30))) |
http://rosettacode.org/wiki/Factors_of_an_integer | Factors of an integer |
Basic Data Operation
This is a basic data operation. It represents a fundamental action on a basic data type.
You may see other such operations in the Basic Data Operations category, or:
Integer Operations
Arithmetic |
Comparison
Boolean Operations
Bitwise |
Logical
String Operations
Concatenation |
Interpolation |
Comparison |
Matching
Memory Operations
Pointers & references |
Addresses
Task
Compute the factors of a positive integer.
These factors are the positive integers by which the number being factored can be divided to yield a positive integer result.
(Though the concepts function correctly for zero and negative integers, the set of factors of zero has countably infinite members, and the factors of negative integers can be obtained from the factors of related positive numbers without difficulty; this task does not require handling of either of these cases).
Note that every prime number has two factors: 1 and itself.
Related tasks
count in factors
prime decomposition
Sieve of Eratosthenes
primality by trial division
factors of a Mersenne number
trial factoring of a Mersenne number
partition an integer X into N primes
sequence of primes by Trial Division
sequence: smallest number greater than previous term with exactly n divisors
| #Ursala | Ursala | #import std
#import nat
factors "n" = (filter not remainder/"n") nrange(1,"n") |
http://rosettacode.org/wiki/Factors_of_an_integer | Factors of an integer |
Basic Data Operation
This is a basic data operation. It represents a fundamental action on a basic data type.
You may see other such operations in the Basic Data Operations category, or:
Integer Operations
Arithmetic |
Comparison
Boolean Operations
Bitwise |
Logical
String Operations
Concatenation |
Interpolation |
Comparison |
Matching
Memory Operations
Pointers & references |
Addresses
Task
Compute the factors of a positive integer.
These factors are the positive integers by which the number being factored can be divided to yield a positive integer result.
(Though the concepts function correctly for zero and negative integers, the set of factors of zero has countably infinite members, and the factors of negative integers can be obtained from the factors of related positive numbers without difficulty; this task does not require handling of either of these cases).
Note that every prime number has two factors: 1 and itself.
Related tasks
count in factors
prime decomposition
Sieve of Eratosthenes
primality by trial division
factors of a Mersenne number
trial factoring of a Mersenne number
partition an integer X into N primes
sequence of primes by Trial Division
sequence: smallest number greater than previous term with exactly n divisors
| #VBA | VBA | Function Factors(x As Integer) As String
Application.Volatile
Dim i As Integer
Dim cooresponding_factors As String
Factors = 1
corresponding_factors = x
For i = 2 To Sqr(x)
If x Mod i = 0 Then
Factors = Factors & ", " & i
If i <> x / i Then corresponding_factors = x / i & ", " & corresponding_factors
End If
Next i
If x <> 1 Then Factors = Factors & ", " & corresponding_factors
End Function |
http://rosettacode.org/wiki/Execute_HQ9%2B | Execute HQ9+ | Task
Implement a HQ9+ interpreter or compiler.
| #Liberty_BASIC | Liberty BASIC | 'Try this hq9+ program - "hq9+HqQ+Qq"
Prompt "Please input your hq9+ program."; code$
Print hq9plus$(code$)
End
Function hq9plus$(code$)
For i = 1 to Len(code$)
Select Case
Case Upper$(Mid$(code$, i, 1)) = "H"
hq9plus$ = hq9plus$ + "Hello, world!"
Case Upper$(Mid$(code$, i, 1)) = "Q"
hq9plus$ = hq9plus$ + code$
Case Mid$(code$, i, 1) = "9"
For bottles = 99 To 1 Step -1
hq9plus$ = hq9plus$ + str$(bottles) + " bottle"
If (bottles > 1) Then hq9plus$ = hq9plus$ + "s"
hq9plus$ = hq9plus$ + " of beer on the wall, " + str$(bottles) + " bottle"
If (bottles > 1) Then hq9plus$ = hq9plus$ + "s"
hq9plus$ = hq9plus$ + " of beer," + chr$(13) + chr$(10) + "Take one down, pass it around, " + str$(bottles - 1) + " bottle"
If (bottles > 2) Or (bottles = 1) Then hq9plus$ = hq9plus$ + "s"
hq9plus$ = hq9plus$ + " of beer on the wall." + chr$(13) + chr$(10)
Next bottles
hq9plus$ = hq9plus$ + "No more bottles of beer on the wall, no more bottles of beer." _
+ chr$(13) + chr$(10) + "Go to the store and buy some more, 99 bottles of beer on the wall."
Case Mid$(code$, i, 1) = "+"
accumulator = (accumulator + 1)
End Select
If Mid$(code$, i, 1) <> "+" Then
hq9plus$ = hq9plus$ + chr$(13) + chr$(10)
End If
Next i
hq9plus$ = Left$(hq9plus$, (Len(hq9plus$) - 2))
End Function |
http://rosettacode.org/wiki/Execute_a_Markov_algorithm | Execute a Markov algorithm | Execute a Markov algorithm
You are encouraged to solve this task according to the task description, using any language you may know.
Task
Create an interpreter for a Markov Algorithm.
Rules have the syntax:
<ruleset> ::= ((<comment> | <rule>) <newline>+)*
<comment> ::= # {<any character>}
<rule> ::= <pattern> <whitespace> -> <whitespace> [.] <replacement>
<whitespace> ::= (<tab> | <space>) [<whitespace>]
There is one rule per line.
If there is a . (period) present before the <replacement>, then this is a terminating rule in which case the interpreter must halt execution.
A ruleset consists of a sequence of rules, with optional comments.
Rulesets
Use the following tests on entries:
Ruleset 1
# This rules file is extracted from Wikipedia:
# http://en.wikipedia.org/wiki/Markov_Algorithm
A -> apple
B -> bag
S -> shop
T -> the
the shop -> my brother
a never used -> .terminating rule
Sample text of:
I bought a B of As from T S.
Should generate the output:
I bought a bag of apples from my brother.
Ruleset 2
A test of the terminating rule
# Slightly modified from the rules on Wikipedia
A -> apple
B -> bag
S -> .shop
T -> the
the shop -> my brother
a never used -> .terminating rule
Sample text of:
I bought a B of As from T S.
Should generate:
I bought a bag of apples from T shop.
Ruleset 3
This tests for correct substitution order and may trap simple regexp based replacement routines if special regexp characters are not escaped.
# BNF Syntax testing rules
A -> apple
WWWW -> with
Bgage -> ->.*
B -> bag
->.* -> money
W -> WW
S -> .shop
T -> the
the shop -> my brother
a never used -> .terminating rule
Sample text of:
I bought a B of As W my Bgage from T S.
Should generate:
I bought a bag of apples with my money from T shop.
Ruleset 4
This tests for correct order of scanning of rules, and may trap replacement routines that scan in the wrong order. It implements a general unary multiplication engine. (Note that the input expression must be placed within underscores in this implementation.)
### Unary Multiplication Engine, for testing Markov Algorithm implementations
### By Donal Fellows.
# Unary addition engine
_+1 -> _1+
1+1 -> 11+
# Pass for converting from the splitting of multiplication into ordinary
# addition
1! -> !1
,! -> !+
_! -> _
# Unary multiplication by duplicating left side, right side times
1*1 -> x,@y
1x -> xX
X, -> 1,1
X1 -> 1X
_x -> _X
,x -> ,X
y1 -> 1y
y_ -> _
# Next phase of applying
1@1 -> x,@y
1@_ -> @_
,@_ -> !_
++ -> +
# Termination cleanup for addition
_1 -> 1
1+_ -> 1
_+_ ->
Sample text of:
_1111*11111_
should generate the output:
11111111111111111111
Ruleset 5
A simple Turing machine,
implementing a three-state busy beaver.
The tape consists of 0s and 1s, the states are A, B, C and H (for Halt), and the head position is indicated by writing the state letter before the character where the head is.
All parts of the initial tape the machine operates on have to be given in the input.
Besides demonstrating that the Markov algorithm is Turing-complete, it also made me catch a bug in the C++ implementation which wasn't caught by the first four rulesets.
# Turing machine: three-state busy beaver
#
# state A, symbol 0 => write 1, move right, new state B
A0 -> 1B
# state A, symbol 1 => write 1, move left, new state C
0A1 -> C01
1A1 -> C11
# state B, symbol 0 => write 1, move left, new state A
0B0 -> A01
1B0 -> A11
# state B, symbol 1 => write 1, move right, new state B
B1 -> 1B
# state C, symbol 0 => write 1, move left, new state B
0C0 -> B01
1C0 -> B11
# state C, symbol 1 => write 1, move left, halt
0C1 -> H01
1C1 -> H11
This ruleset should turn
000000A000000
into
00011H1111000
| #J | J | require'strings regex'
markovLexer =: verb define
rules =. LF cut TAB&=`(,:&' ')}y
rules =. a: -.~ (dltb@:{.~ i:&'#')&.> rules
rules =. 0 _1 {"1 '\s+->\s+' (rxmatch rxcut ])S:0 rules
(,. ] (}.&.>~ ,. ]) ('.'={.)&.>)/ |: rules
)
replace =: dyad define
'index patternLength replacement'=. x
'head tail' =. index split y
head, replacement, patternLength }. tail
)
matches =: E. i. 1:
markov =: dyad define
ruleIdx =. 0 [ rules =. markovLexer x
while. ruleIdx < #rules do.
'pattern replacement terminating' =. ruleIdx { rules
ruleIdx =. 1 + ruleIdx
if. (#y) > index =. pattern matches y do.
y =. (index ; (#pattern) ; replacement) replace y
ruleIdx =. _ * terminating
end.
end.
y
) |
http://rosettacode.org/wiki/Exceptions/Catch_an_exception_thrown_in_a_nested_call | Exceptions/Catch an exception thrown in a nested call | Show how to create a user-defined exception and show how to catch an exception raised from several nested calls away.
Create two user-defined exceptions, U0 and U1.
Have function foo call function bar twice.
Have function bar call function baz.
Arrange for function baz to raise, or throw exception U0 on its first call, then exception U1 on its second.
Function foo should catch only exception U0, not U1.
Show/describe what happens when the program is run.
| #jq | jq | # n is assumed to be the number of times baz has been previously called:
def baz(n):
if n==0 then error("U0")
elif n==1 then error("U1")
else "Goodbye"
end;
def bar(n): baz(n);
def foo:
(try bar(0) catch if . == "U0" then "We caught U0" else error(.) end),
(try bar(1) catch if . == "U0" then "We caught U0" else error(.) end);
foo |
http://rosettacode.org/wiki/Exceptions/Catch_an_exception_thrown_in_a_nested_call | Exceptions/Catch an exception thrown in a nested call | Show how to create a user-defined exception and show how to catch an exception raised from several nested calls away.
Create two user-defined exceptions, U0 and U1.
Have function foo call function bar twice.
Have function bar call function baz.
Arrange for function baz to raise, or throw exception U0 on its first call, then exception U1 on its second.
Function foo should catch only exception U0, not U1.
Show/describe what happens when the program is run.
| #Julia | Julia | struct U0 <: Exception end
struct U1 <: Exception end
function foo()
for i in 1:2
try
bar()
catch err
if isa(err, U0) println("catched U0")
else rethrow(err) end
end
end
end
function bar()
baz()
end
function baz()
if isdefined(:_called) && _called
throw(U1())
else
global _called = true
throw(U0())
end
end
foo() |
http://rosettacode.org/wiki/Exceptions/Catch_an_exception_thrown_in_a_nested_call | Exceptions/Catch an exception thrown in a nested call | Show how to create a user-defined exception and show how to catch an exception raised from several nested calls away.
Create two user-defined exceptions, U0 and U1.
Have function foo call function bar twice.
Have function bar call function baz.
Arrange for function baz to raise, or throw exception U0 on its first call, then exception U1 on its second.
Function foo should catch only exception U0, not U1.
Show/describe what happens when the program is run.
| #Kotlin | Kotlin | // version 1.0.6
class U0 : Throwable("U0 occurred")
class U1 : Throwable("U1 occurred")
fun foo() {
for (i in 1..2) {
try {
bar(i)
} catch(e: U0) {
println(e.message)
}
}
}
fun bar(i: Int) {
baz(i)
}
fun baz(i: Int) {
when (i) {
1 -> throw U0()
2 -> throw U1()
}
}
fun main(args: Array<String>) {
foo()
} |
http://rosettacode.org/wiki/Exceptions | Exceptions | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
This task is to give an example of an exception handling routine
and to "throw" a new exception.
Related task
Exceptions Through Nested Calls
| #Forth | Forth | : f ( -- ) 1 throw ." f " ; \ will throw a "1"
: g ( -- ) 0 throw ." g " ; \ does not throw |
http://rosettacode.org/wiki/Exceptions | Exceptions | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
This task is to give an example of an exception handling routine
and to "throw" a new exception.
Related task
Exceptions Through Nested Calls
| #FreeBASIC | FreeBASIC | ' FB 1.05.0 Win64
Enum ErrorType
myError = 1000
End Enum
Sub foo()
Err = 1000 ' raise a user-defined error
End Sub
Sub callFoo()
foo()
Dim As Long errNo = Err ' cache Err in case it's reset by a different function
Select Case errNo
Case 0
' No error (system defined)
Case 1 To 17
' System defined runtime errors
Case myError: ' catch myError
Print "Caught myError : Error number"; errNo
Case Else
' catch any other type of errors here
End Select
' add any clean-up code here
End Sub
callfoo()
Print
Print "Press any key to quit"
Sleep |
http://rosettacode.org/wiki/Execute_a_system_command | Execute a system command | Task
Run either the ls system command (dir on Windows), or the pause system command.
Related task
Get system command output
| #DBL | DBL | XCALL SPAWN ("ls *.jpg > file.txt") ;execute command and continue
XCALL EXEC ("script.sh") ;execute script or binary and exit
STOP '@/bin/ls *.jpg > file.txt' ;exit and execute command |
http://rosettacode.org/wiki/Factorial | Factorial | Definitions
The factorial of 0 (zero) is defined as being 1 (unity).
The Factorial Function of a positive integer, n, is defined as the product of the sequence:
n, n-1, n-2, ... 1
Task
Write a function to return the factorial of a number.
Solutions can be iterative or recursive.
Support for trapping negative n errors is optional.
Related task
Primorial numbers
| #Applesoft_BASIC | Applesoft BASIC | 100 N = 4 : GOSUB 200"FACTORIAL
110 PRINT N
120 END
200 N = INT(N)
210 IF N > 1 THEN FOR I = N - 1 TO 2 STEP -1 : N = N * I : NEXT I
220 RETURN |
http://rosettacode.org/wiki/Exponentiation_operator | Exponentiation operator | Most programming languages have a built-in implementation of exponentiation.
Task
Re-implement integer exponentiation for both intint and floatint as both a procedure, and an operator (if your language supports operator definition).
If the language supports operator (or procedure) overloading, then an overloaded form should be provided for both intint and floatint variants.
Related tasks
Exponentiation order
arbitrary-precision integers (included)
Exponentiation with infix operators in (or operating on) the base
| #Lambdatalk | Lambdatalk |
{def ^
{def *^
{lambda {:base :exponent :acc}
{if {= :exponent 0}
then :acc
else {*^ :base {- :exponent 1} {* :acc :base}}}}}
{lambda {:base :exponent}
{*^ :base :exponent 1}}}
-> ^
{^ 2 3}
-> 8
{^ {/ 1 2} 3}
-> 0.125 // No rational type as primitives
{^ 0.5 3}
-> 0.125
|
http://rosettacode.org/wiki/Exponentiation_operator | Exponentiation operator | Most programming languages have a built-in implementation of exponentiation.
Task
Re-implement integer exponentiation for both intint and floatint as both a procedure, and an operator (if your language supports operator definition).
If the language supports operator (or procedure) overloading, then an overloaded form should be provided for both intint and floatint variants.
Related tasks
Exponentiation order
arbitrary-precision integers (included)
Exponentiation with infix operators in (or operating on) the base
| #Liberty_BASIC | Liberty BASIC |
print " 11^5 = ", floatPow( 11, 5 )
print " (-11)^5 = ", floatPow( -11, 5 )
print " 11^( -5) = ", floatPow( 11, -5 )
print " 3.1416^3 = ", floatPow( 3.1416, 3 )
print " 0^2 = ", floatPow( 0, 2 )
print " 2^0 = ", floatPow( 2, 0 )
print " -2^0 = ", floatPow( -2, 0 )
end
function floatPow( a, b)
if a <>0 then
m =1
if b =abs( b) then
for n =1 to b
m =m *a
next n
else
m =1 /floatPow( a, 0 - b) ' LB has no unitary minus operator.
end if
else
m =0
end if
floatPow =m
end function
|
http://rosettacode.org/wiki/Extend_your_language | Extend your language | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
Some programming languages allow you to extend the language. While this can be done to a certain degree in most languages (e.g. by using macros), other languages go much further. Most notably in the Forth and Lisp families, programming per se is done by extending the language without any formal distinction between built-in and user-defined elements.
If your language supports it, show how to introduce a new flow control mechanism. A practical and useful example is a four-way branch:
Occasionally, code must be written that depends on two conditions, resulting in up to four branches (depending on whether both, only the first, only the second, or none of the conditions are "true"). In a C-like language this could look like the following:
if (condition1isTrue) {
if (condition2isTrue)
bothConditionsAreTrue();
else
firstConditionIsTrue();
}
else if (condition2isTrue)
secondConditionIsTrue();
else
noConditionIsTrue();
Besides being rather cluttered, the statement(s) for 'condition2isTrue' must be written down twice. If 'condition2isTrue' were a lengthy and involved expression, it would be quite unreadable, and the code generated by the compiler might be unnecessarily large.
This can be improved by introducing a new keyword if2. It is similar to if, but takes two conditional statements instead of one, and up to three 'else' statements. One proposal (in pseudo-C syntax) might be:
if2 (condition1isTrue) (condition2isTrue)
bothConditionsAreTrue();
else1
firstConditionIsTrue();
else2
secondConditionIsTrue();
else
noConditionIsTrue();
Pick the syntax which suits your language. The keywords 'else1' and 'else2' are just examples. The new conditional expression should look, nest and behave analogously to the language's built-in 'if' statement.
| #PowerShell | PowerShell |
function When-Condition
{
[CmdletBinding()]
Param
(
[Parameter(Mandatory=$true, Position=0)]
[bool]
$Test1,
[Parameter(Mandatory=$true, Position=1)]
[bool]
$Test2,
[Parameter(Mandatory=$true, Position=2)]
[scriptblock]
$Both,
[Parameter(Mandatory=$true, Position=3)]
[scriptblock]
$First,
[Parameter(Mandatory=$true, Position=4)]
[scriptblock]
$Second,
[Parameter(Mandatory=$true, Position=5)]
[scriptblock]
$Neither
)
if ($Test1 -and $Test2)
{
return (&$Both)
}
elseif ($Test1 -and -not $Test2)
{
return (&$First)
}
elseif (-not $Test1 -and $Test2)
{
return (&$Second)
}
else
{
return (&$Neither)
}
}
|
http://rosettacode.org/wiki/FizzBuzz | FizzBuzz | Task
Write a program that prints the integers from 1 to 100 (inclusive).
But:
for multiples of three, print Fizz (instead of the number)
for multiples of five, print Buzz (instead of the number)
for multiples of both three and five, print FizzBuzz (instead of the number)
The FizzBuzz problem was presented as the lowest level of comprehension required to illustrate adequacy.
Also see
(a blog) dont-overthink-fizzbuzz
(a blog) fizzbuzz-the-programmers-stairway-to-heaven
| #Salmon | Salmon | iterate (x; [1...100])
((x % 15 == 0) ? "FizzBuzz" :
((x % 3 == 0) ? "Fizz" :
((x % 5 == 0) ? "Buzz" : x)))!; |
http://rosettacode.org/wiki/Extensible_prime_generator | Extensible prime generator | Task
Write a generator of prime numbers, in order, that will automatically adjust to accommodate the generation of any reasonably high prime.
The routine should demonstrably rely on either:
Being based on an open-ended counter set to count without upper limit other than system or programming language limits. In this case, explain where this counter is in the code.
Being based on a limit that is extended automatically. In this case, choose a small limit that ensures the limit will be passed when generating some of the values to be asked for below.
If other methods of creating an extensible prime generator are used, the algorithm's means of extensibility/lack of limits should be stated.
The routine should be used to:
Show the first twenty primes.
Show the primes between 100 and 150.
Show the number of primes between 7,700 and 8,000.
Show the 10,000th prime.
Show output on this page.
Note: You may reference code already on this site if it is written to be imported/included, then only the code necessary for import and the performance of this task need be shown. (It is also important to leave a forward link on the referenced tasks entry so that later editors know that the code is used for multiple tasks).
Note 2: If a languages in-built prime generator is extensible or is guaranteed to generate primes up to a system limit, (231 or memory overflow for example), then this may be used as long as an explanation of the limits of the prime generator is also given. (Which may include a link to/excerpt from, language documentation).
Note 3:The task is written so it may be useful in solving the task Emirp primes as well as others (depending on its efficiency).
Reference
Prime Numbers. Website with large count of primes.
| #PureBasic | PureBasic | EnableExplicit
DisableDebugger
Define StartTime.i=ElapsedMilliseconds()
Procedure.b IsPrime(n.i)
Define i.i=5
If n<2 : ProcedureReturn #False : EndIf
If n%2=0 : ProcedureReturn Bool(n=2) : EndIf
If n%3=0 : ProcedureReturn Bool(n=3) : EndIf
While i*i<=n
If n%i=0 : ProcedureReturn #False : EndIf
i+2
If n%i=0 : ProcedureReturn #False : EndIf
i+4
Wend
ProcedureReturn #True
EndProcedure
If OpenConsole("Extensible prime generator")
Define c.i=0, n.i=2
Print("First twenty: ")
While c<20
If IsPrime(n)
Print(Str(n)+" ")
c+1
EndIf
n+1
Wend
Print(~"\nBetween 100 and 150: ")
For n=100 To 150
If IsPrime(n)
Print(Str(n)+" ")
EndIf
Next
Print(~"\nNumber beween 7'700 and 8'000: ")
c=0
For n=7700 To 8000
c+IsPrime(n)
Next
Print(Str(c))
Print(~"\n10'000th prime: ")
c=0 : n=1
While c<10000
n+1
c+IsPrime(n)
Wend
Print(Str(n))
EndIf
Print(~"\nRuntime milliseconds: "+
Str(ElapsedMilliseconds()-StartTime))
Input() |
http://rosettacode.org/wiki/Execute_Brain**** | Execute Brain**** | Execute Brain**** is an implementation of Brainf***.
Other implementations of Brainf***.
RCBF is a set of Brainf*** compilers and interpreters written for Rosetta Code in a variety of languages.
Below are links to each of the versions of RCBF.
An implementation need only properly implement the following instructions:
Command
Description
>
Move the pointer to the right
<
Move the pointer to the left
+
Increment the memory cell under the pointer
-
Decrement the memory cell under the pointer
.
Output the character signified by the cell at the pointer
,
Input a character and store it in the cell at the pointer
[
Jump past the matching ] if the cell under the pointer is 0
]
Jump back to the matching [ if the cell under the pointer is nonzero
Any cell size is allowed, EOF (End-O-File) support is optional, as is whether you have bounded or unbounded memory.
| #AWK | AWK | BEGIN {
bf=ARGV[1]; ARGV[1] = ""
compile(bf)
execute()
}
# Strips non-instructions, builds the jump table.
function compile(s, i,j,k,f) {
c = split(s, src, "")
j = 0
for(i = 1; i <= c; i++) {
if(src[i] ~ /[\-\+\[\]\<\>,\.]/)
code[j++] = src[i]
if(src[i] == "[") {
marks[j] = 1
} else if(src[i] == "]") {
f = 0
for(k = j; k > 0; k--) {
if(k in marks) {
jump[k-1] = j - 1
jump[j-1] = k - 1
f = 1
delete marks[k]
break
}
}
if(!f) {
print "Unmatched ]"
exit 1
}
}
}
}
function execute( pc,p,i) {
pc = p = 0
while(pc in code) {
i = code[pc]
if(i == "+")
arena[p]++
else if(i == "-")
arena[p]--
else if(i == "<")
p--
else if(i == ">")
p++
else if(i == ".")
printf("%c", arena[p])
else if(i == ",") {
while(1) {
if (goteof) break
if (!gotline) {
gotline = getline
if(!gotline) goteof = 1
if (goteof) break
line = $0
}
if (line == "") {
gotline=0
m[p]=10
break
}
if (!genord) {
for(i=1; i<256; i++)
ord[sprintf("%c",i)] = i
genord=1
}
c = substr(line, 1, 1)
line=substr(line, 2)
arena[p] = ord[c]
break
}
} else if((i == "[" && arena[p] == 0) ||
(i == "]" && arena[p] != 0))
pc = jump[pc]
pc++
}
}
|
http://rosettacode.org/wiki/Evolutionary_algorithm | Evolutionary algorithm | Starting with:
The target string: "METHINKS IT IS LIKE A WEASEL".
An array of random characters chosen from the set of upper-case letters together with the space, and of the same length as the target string. (Call it the parent).
A fitness function that computes the ‘closeness’ of its argument to the target string.
A mutate function that given a string and a mutation rate returns a copy of the string, with some characters probably mutated.
While the parent is not yet the target:
copy the parent C times, each time allowing some random probability that another character might be substituted using mutate.
Assess the fitness of the parent and all the copies to the target and make the most fit string the new parent, discarding the others.
repeat until the parent converges, (hopefully), to the target.
See also
Wikipedia entry: Weasel algorithm.
Wikipedia entry: Evolutionary algorithm.
Note: to aid comparison, try and ensure the variables and functions mentioned in the task description appear in solutions
A cursory examination of a few of the solutions reveals that the instructions have not been followed rigorously in some solutions. Specifically,
While the parent is not yet the target:
copy the parent C times, each time allowing some random probability that another character might be substituted using mutate.
Note that some of the the solutions given retain characters in the mutated string that are correct in the target string. However, the instruction above does not state to retain any of the characters while performing the mutation. Although some may believe to do so is implied from the use of "converges"
(:* repeat until the parent converges, (hopefully), to the target.
Strictly speaking, the new parent should be selected from the new pool of mutations, and then the new parent used to generate the next set of mutations with parent characters getting retained only by not being mutated. It then becomes possible that the new set of mutations has no member that is fitter than the parent!
As illustration of this error, the code for 8th has the following remark.
Create a new string based on the TOS, changing randomly any characters which
don't already match the target:
NOTE: this has been changed, the 8th version is completely random now
Clearly, this algo will be applying the mutation function only to the parent characters that don't match to the target characters!
To ensure that the new parent is never less fit than the prior parent, both the parent and all of the latest mutations are subjected to the fitness test to select the next parent.
| #BBC_BASIC | BBC BASIC | target$ = "METHINKS IT IS LIKE A WEASEL"
parent$ = "IU RFSGJABGOLYWF XSMFXNIABKT"
mutation_rate = 0.5
children% = 10
DIM child$(children%)
REPEAT
bestfitness = 0
bestindex% = 0
FOR index% = 1 TO children%
child$(index%) = FNmutate(parent$, mutation_rate)
fitness = FNfitness(target$, child$(index%))
IF fitness > bestfitness THEN
bestfitness = fitness
bestindex% = index%
ENDIF
NEXT index%
parent$ = child$(bestindex%)
PRINT parent$
UNTIL parent$ = target$
END
DEF FNfitness(text$, ref$)
LOCAL I%, F%
FOR I% = 1 TO LEN(text$)
IF MID$(text$, I%, 1) = MID$(ref$, I%, 1) THEN F% += 1
NEXT
= F% / LEN(text$)
DEF FNmutate(text$, rate)
LOCAL C%
IF rate > RND(1) THEN
C% = 63+RND(27)
IF C% = 64 C% = 32
MID$(text$, RND(LEN(text$)), 1) = CHR$(C%)
ENDIF
= text$ |
http://rosettacode.org/wiki/Fibonacci_sequence | Fibonacci sequence | The Fibonacci sequence is a sequence Fn of natural numbers defined recursively:
F0 = 0
F1 = 1
Fn = Fn-1 + Fn-2, if n>1
Task
Write a function to generate the nth Fibonacci number.
Solutions can be iterative or recursive (though recursive solutions are generally considered too slow and are mostly used as an exercise in recursion).
The sequence is sometimes extended into negative numbers by using a straightforward inverse of the positive definition:
Fn = Fn+2 - Fn+1, if n<0
support for negative n in the solution is optional.
Related tasks
Fibonacci n-step number sequences
Leonardo numbers
References
Wikipedia, Fibonacci number
Wikipedia, Lucas number
MathWorld, Fibonacci Number
Some identities for r-Fibonacci numbers
OEIS Fibonacci numbers
OEIS Lucas numbers
| #LabVIEW | LabVIEW |
1) basic version
{def fib1
{lambda {:n}
{if {< :n 3}
then 1
else {+ {fib1 {- :n 1}} {fib1 {- :n 2}}} }}}
{fib1 16} -> 987 (CPU ~ 16ms)
{fib1 30} = 832040 (CPU > 12000ms)
2) tail-recursive version
{def fib2
{def fib2.r
{lambda {:a :b :i}
{if {< :i 1}
then :a
else {fib2.r :b {+ :a :b} {- :i 1}} }}}
{lambda {:n} {fib2.r 0 1 :n}}}
{fib2 16} -> 987 (CPU ~ 1ms)
{fib2 30} -> 832040 (CPU ~2ms)
{fib2 1000} -> 4.346655768693743e+208 (CPU ~ 22ms)
3) Dijkstra Algorithm
{def fib3
{def fib3.r
{lambda {:a :b :p :q :count}
{if {= :count 0}
then :b
else {if {= {% :count 2} 0}
then {fib3.r :a :b
{+ {* :p :p} {* :q :q}}
{+ {* :q :q} {* 2 :p :q}}
{/ :count 2}}
else {fib3.r {+ {* :b :q} {* :a :q} {* :a :p}}
{+ {* :b :p} {* :a :q}}
:p :q
{- :count 1}} }}}}
{lambda {:n}
{fib3.r 1 0 0 1 :n} }}
{fib3 16} -> 987 (CPU ~ 2ms)
{fib3 30} -> 832040 (CPU ~ 2ms)
{fib3 1000} -> 4.346655768693743e+208 (CPU ~ 3ms)
4) memoization
{def fib4
{def fib4.m {array.new}} // init an empty array
{def fib4.r {lambda {:n}
{if {< :n 2}
then {array.get {array.set! {fib4.m} :n 1} :n} // init with 1,1
else {if {equal? {array.get {fib4.m} :n} undefined} // if not exists
then {array.get {array.set! {fib4.m} :n
{+ {fib4.r {- :n 1}}
{fib4.r {- :n 2}}}} :n} // compute it
else {array.get {fib4.m} :n} }}}} // else get it
{lambda {:n}
{fib4.r :n}
{fib4.m} }} // display the number AND all its predecessors
-> fib4
{fib4 90}
-> 4660046610375530000
[1,1,2,3,5,8,13,21,34,55,89,144,233,377,610,987,1597,2584,4181,6765,10946,17711,28657,46368,75025,121393,196418,
317811,514229,832040,1346269,2178309,3524578,5702887,9227465,14930352,24157817,39088169,63245986,102334155,
165580141,267914296,433494437,701408733,1134903170,1836311903,2971215073,4807526976,7778742049,12586269025,
20365011074,32951280099,53316291173,86267571272,139583862445,225851433717,365435296162,591286729879,956722026041,
1548008755920,2504730781961,4052739537881,6557470319842,10610209857723,17167680177565,27777890035288,44945570212853,
72723460248141,117669030460994,190392490709135,308061521170129,498454011879264,806515533049393,1304969544928657,
2111485077978050,3416454622906707,5527939700884757,8944394323791464,14472334024676220,23416728348467684,
37889062373143900,61305790721611580,99194853094755490,160500643816367070,259695496911122560,420196140727489660,
679891637638612200,1100087778366101900,1779979416004714000,2880067194370816000,4660046610375530000]
5) Binet's formula (non recursive)
{def fib5
{lambda {:n}
{let { {:n :n} {:sqrt5 {sqrt 5}} }
{round {/ {- {pow {/ {+ 1 :sqrt5} 2} :n}
{pow {/ {- 1 :sqrt5} 2} :n}} :sqrt5}}} }}
{fib5 16} -> 987 (CPU ~ 1ms)
{fib5 30} -> 832040 (CPU ~ 1ms)
{fib5 1000} -> 4.346655768693743e+208 (CPU ~ 1ms)
|
http://rosettacode.org/wiki/Factors_of_an_integer | Factors of an integer |
Basic Data Operation
This is a basic data operation. It represents a fundamental action on a basic data type.
You may see other such operations in the Basic Data Operations category, or:
Integer Operations
Arithmetic |
Comparison
Boolean Operations
Bitwise |
Logical
String Operations
Concatenation |
Interpolation |
Comparison |
Matching
Memory Operations
Pointers & references |
Addresses
Task
Compute the factors of a positive integer.
These factors are the positive integers by which the number being factored can be divided to yield a positive integer result.
(Though the concepts function correctly for zero and negative integers, the set of factors of zero has countably infinite members, and the factors of negative integers can be obtained from the factors of related positive numbers without difficulty; this task does not require handling of either of these cases).
Note that every prime number has two factors: 1 and itself.
Related tasks
count in factors
prime decomposition
Sieve of Eratosthenes
primality by trial division
factors of a Mersenne number
trial factoring of a Mersenne number
partition an integer X into N primes
sequence of primes by Trial Division
sequence: smallest number greater than previous term with exactly n divisors
| #Verilog | Verilog |
module main;
integer i, n;
initial begin
n = 45;
$write(n, " =>");
for(i = 1; i <= n / 2; i = i + 1) if(n % i == 0) $write(i);
$display(n);
$finish ;
end
endmodule
|
http://rosettacode.org/wiki/Execute_HQ9%2B | Execute HQ9+ | Task
Implement a HQ9+ interpreter or compiler.
| #Lua | Lua |
function runCode( code )
local acc, lc = 0
for i = 1, #code do
lc = code:sub( i, i ):upper()
if lc == "Q" then print( lc )
elseif lc == "H" then print( "Hello, World!" )
elseif lc == "+" then acc = acc + 1
elseif lc == "9" then
for j = 99, 1, -1 do
if j > 1 then
print( string.format( "%d bottles of beer on the wall\n%d bottles of beer\nTake one down, pass it around\n%d bottles of beer on the wall\n", j, j, j - 1 ) )
else
print( "1 bottle of beer on the wall\n1 bottle of beer\nTake one down and pass it around\nno more bottles of beer on the wall\n\n"..
"No more bottles of beer on the wall\nNo more bottles of beer\n"..
"Go to the store and buy some more\n99 bottles of beer on the wall.\n" )
end
end
end
end
end
|
http://rosettacode.org/wiki/Execute_a_Markov_algorithm | Execute a Markov algorithm | Execute a Markov algorithm
You are encouraged to solve this task according to the task description, using any language you may know.
Task
Create an interpreter for a Markov Algorithm.
Rules have the syntax:
<ruleset> ::= ((<comment> | <rule>) <newline>+)*
<comment> ::= # {<any character>}
<rule> ::= <pattern> <whitespace> -> <whitespace> [.] <replacement>
<whitespace> ::= (<tab> | <space>) [<whitespace>]
There is one rule per line.
If there is a . (period) present before the <replacement>, then this is a terminating rule in which case the interpreter must halt execution.
A ruleset consists of a sequence of rules, with optional comments.
Rulesets
Use the following tests on entries:
Ruleset 1
# This rules file is extracted from Wikipedia:
# http://en.wikipedia.org/wiki/Markov_Algorithm
A -> apple
B -> bag
S -> shop
T -> the
the shop -> my brother
a never used -> .terminating rule
Sample text of:
I bought a B of As from T S.
Should generate the output:
I bought a bag of apples from my brother.
Ruleset 2
A test of the terminating rule
# Slightly modified from the rules on Wikipedia
A -> apple
B -> bag
S -> .shop
T -> the
the shop -> my brother
a never used -> .terminating rule
Sample text of:
I bought a B of As from T S.
Should generate:
I bought a bag of apples from T shop.
Ruleset 3
This tests for correct substitution order and may trap simple regexp based replacement routines if special regexp characters are not escaped.
# BNF Syntax testing rules
A -> apple
WWWW -> with
Bgage -> ->.*
B -> bag
->.* -> money
W -> WW
S -> .shop
T -> the
the shop -> my brother
a never used -> .terminating rule
Sample text of:
I bought a B of As W my Bgage from T S.
Should generate:
I bought a bag of apples with my money from T shop.
Ruleset 4
This tests for correct order of scanning of rules, and may trap replacement routines that scan in the wrong order. It implements a general unary multiplication engine. (Note that the input expression must be placed within underscores in this implementation.)
### Unary Multiplication Engine, for testing Markov Algorithm implementations
### By Donal Fellows.
# Unary addition engine
_+1 -> _1+
1+1 -> 11+
# Pass for converting from the splitting of multiplication into ordinary
# addition
1! -> !1
,! -> !+
_! -> _
# Unary multiplication by duplicating left side, right side times
1*1 -> x,@y
1x -> xX
X, -> 1,1
X1 -> 1X
_x -> _X
,x -> ,X
y1 -> 1y
y_ -> _
# Next phase of applying
1@1 -> x,@y
1@_ -> @_
,@_ -> !_
++ -> +
# Termination cleanup for addition
_1 -> 1
1+_ -> 1
_+_ ->
Sample text of:
_1111*11111_
should generate the output:
11111111111111111111
Ruleset 5
A simple Turing machine,
implementing a three-state busy beaver.
The tape consists of 0s and 1s, the states are A, B, C and H (for Halt), and the head position is indicated by writing the state letter before the character where the head is.
All parts of the initial tape the machine operates on have to be given in the input.
Besides demonstrating that the Markov algorithm is Turing-complete, it also made me catch a bug in the C++ implementation which wasn't caught by the first four rulesets.
# Turing machine: three-state busy beaver
#
# state A, symbol 0 => write 1, move right, new state B
A0 -> 1B
# state A, symbol 1 => write 1, move left, new state C
0A1 -> C01
1A1 -> C11
# state B, symbol 0 => write 1, move left, new state A
0B0 -> A01
1B0 -> A11
# state B, symbol 1 => write 1, move right, new state B
B1 -> 1B
# state C, symbol 0 => write 1, move left, new state B
0C0 -> B01
1C0 -> B11
# state C, symbol 1 => write 1, move left, halt
0C1 -> H01
1C1 -> H11
This ruleset should turn
000000A000000
into
00011H1111000
| #Java | Java | import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Markov {
public static void main(String[] args) throws IOException {
List<String[]> rules = readRules("markov_rules.txt");
List<String> tests = readTests("markov_tests.txt");
Pattern pattern = Pattern.compile("^([^#]*?)\\s+->\\s+(\\.?)(.*)");
for (int i = 0; i < tests.size(); i++) {
String origTest = tests.get(i);
List<String[]> captures = new ArrayList<>();
for (String rule : rules.get(i)) {
Matcher m = pattern.matcher(rule);
if (m.find()) {
String[] groups = new String[m.groupCount()];
for (int j = 0; j < groups.length; j++)
groups[j] = m.group(j + 1);
captures.add(groups);
}
}
String test = origTest;
String copy = test;
for (int j = 0; j < captures.size(); j++) {
String[] c = captures.get(j);
test = test.replace(c[0], c[2]);
if (c[1].equals("."))
break;
if (!test.equals(copy)) {
j = -1; // redo loop
copy = test;
}
}
System.out.printf("%s\n%s\n\n", origTest, test);
}
}
private static List<String> readTests(String path)
throws IOException {
return Files.readAllLines(Paths.get(path), StandardCharsets.UTF_8);
}
private static List<String[]> readRules(String path)
throws IOException {
String ls = System.lineSeparator();
String lines = new String(Files.readAllBytes(Paths.get(path)), "UTF-8");
List<String[]> rules = new ArrayList<>();
for (String line : lines.split(ls + ls))
rules.add(line.split(ls));
return rules;
}
} |
http://rosettacode.org/wiki/Exceptions/Catch_an_exception_thrown_in_a_nested_call | Exceptions/Catch an exception thrown in a nested call | Show how to create a user-defined exception and show how to catch an exception raised from several nested calls away.
Create two user-defined exceptions, U0 and U1.
Have function foo call function bar twice.
Have function bar call function baz.
Arrange for function baz to raise, or throw exception U0 on its first call, then exception U1 on its second.
Function foo should catch only exception U0, not U1.
Show/describe what happens when the program is run.
| #langur | langur | val .U0 = h{"msg": "U0"}
val .U1 = h{"msg": "U1"}
val .baz = f(.i) throw if(.i==0: .U0; .U1)
val .bar = f(.i) .baz(.i)
val .foo = f() {
for .i in [0, 1] {
.bar(.i)
catch if _err["msg"] == .U0["msg"] {
writeln "caught .U0 in .foo()"
} else {
throw
}
}
}
.foo() |
http://rosettacode.org/wiki/Exceptions/Catch_an_exception_thrown_in_a_nested_call | Exceptions/Catch an exception thrown in a nested call | Show how to create a user-defined exception and show how to catch an exception raised from several nested calls away.
Create two user-defined exceptions, U0 and U1.
Have function foo call function bar twice.
Have function bar call function baz.
Arrange for function baz to raise, or throw exception U0 on its first call, then exception U1 on its second.
Function foo should catch only exception U0, not U1.
Show/describe what happens when the program is run.
| #Lasso | Lasso | define try(exception) => {
local(
gb = givenblock,
error
)
handle => {
// Only relay error if it's not the specified exception
if(#error) => {
if(#error->get(2) == #exception) => {
stdoutnl('Handled exception: '+#error->get(2))
else
stdoutnl('Throwing exception: '+#error->get(2))
fail(:#error)
}
}
}
protect => {
handle_error => {
#error = (:error_code,error_msg,error_stack)
}
#gb()
}
}
define foo => {
stdoutnl('foo')
try('U0') => { bar }
try('U0') => { bar }
}
define bar => {
stdoutnl('- bar')
baz()
}
define baz => {
stdoutnl(' - baz')
var(bazzed) ? fail('U1') | $bazzed = true
fail('U0')
} |
http://rosettacode.org/wiki/Exceptions/Catch_an_exception_thrown_in_a_nested_call | Exceptions/Catch an exception thrown in a nested call | Show how to create a user-defined exception and show how to catch an exception raised from several nested calls away.
Create two user-defined exceptions, U0 and U1.
Have function foo call function bar twice.
Have function bar call function baz.
Arrange for function baz to raise, or throw exception U0 on its first call, then exception U1 on its second.
Function foo should catch only exception U0, not U1.
Show/describe what happens when the program is run.
| #Lua | Lua | local baz_counter=1
function baz()
if baz_counter==1 then
baz_counter=baz_counter+1
error("U0",3)--3 sends it down the call stack.
elseif baz_counter==2 then
error("U1",3)--3 sends it down the call stack.
end
end
function bar()
baz()
end
function foo()
function callbar()
local no_err,result = pcall(bar)
--pcall is a protected call which catches errors.
if not no_err then
--If there are no errors, pcall returns true.
if not result:match("U0") then
--If the error is not a U0 error, rethrow it.
error(result,2)
--2 is the distance down the call stack to send
--the error. We want it to go back to the callbar() call.
end
end
end
callbar()
callbar()
end
foo()
|
http://rosettacode.org/wiki/Exceptions | Exceptions | Control Structures
These are examples of control structures. You may also be interested in:
Conditional structures
Exceptions
Flow-control structures
Loops
This task is to give an example of an exception handling routine
and to "throw" a new exception.
Related task
Exceptions Through Nested Calls
| #Gambas | Gambas | Public Sub Main()
Dim iInteger As Integer
MakeError
DivError
iInteger = "2.54"
Catch
Print Error.Text
End
'______________________
Public Sub DivError()
Print 10 / 0
Catch
Print Error.Text
End
'______________________
Public Sub MakeError()
Error.Raise("My Error")
Catch
Print Error.Text
End |
http://rosettacode.org/wiki/Execute_a_system_command | Execute a system command | Task
Run either the ls system command (dir on Windows), or the pause system command.
Related task
Get system command output
| #DCL | DCL | Directory |
http://rosettacode.org/wiki/Execute_a_system_command | Execute a system command | Task
Run either the ls system command (dir on Windows), or the pause system command.
Related task
Get system command output
| #Delphi | Delphi | program ExecuteSystemCommand;
{$APPTYPE CONSOLE}
uses Windows, ShellApi;
begin
ShellExecute(0, nil, 'cmd.exe', ' /c dir', nil, SW_HIDE);
end. |
http://rosettacode.org/wiki/Factorial | Factorial | Definitions
The factorial of 0 (zero) is defined as being 1 (unity).
The Factorial Function of a positive integer, n, is defined as the product of the sequence:
n, n-1, n-2, ... 1
Task
Write a function to return the factorial of a number.
Solutions can be iterative or recursive.
Support for trapping negative n errors is optional.
Related task
Primorial numbers
| #Arendelle | Arendelle | < n >
{ @n = 0 ,
( return , 1 )
,
( return ,
@n * !factorial( @n - ! )
)
}
|
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