task_url
stringlengths
30
116
task_name
stringlengths
2
86
task_description
stringlengths
0
14.4k
language_url
stringlengths
2
53
language_name
stringlengths
1
52
code
stringlengths
0
61.9k
response_seed
stringclasses
1 value
instruction_seed
stringlengths
27
14.4k
_source
stringclasses
1 value
http://rosettacode.org/wiki/Time_a_function
Time a function
Task Write a program which uses a timer (with the least granularity available on your system) to time how long a function takes to execute. Whenever possible, use methods which measure only the processing time used by the current process; instead of the difference in system time between start and finish, which could ...
#Forth
Forth
: time: ( "word" -- ) utime 2>R ' EXECUTE utime 2R> D- <# # # # # # # [CHAR] . HOLD #S #> TYPE ." seconds" ;   1000 time: MS \ 1.000081 seconds ok
Give a code snippet in #Forth Task Write a program which uses a timer (with the least granularity available on your system) to time how long a function takes to execute. Whenever possible, use methods which measure only the processing time used by the current process; instead of the difference in system time between...
christopher/rosetta-code
http://rosettacode.org/wiki/Caesar_cipher
Caesar cipher
Task Implement a Caesar cipher, both encoding and decoding. The key is an integer from 1 to 25. This cipher rotates (either towards left or right) the letters of the alphabet (A to Z). The encoding replaces each letter with the 1st to 25th next letter in the alphabet (wrapping Z to A). So key 2 encrypts "HI" to...
#Commodore_BASIC
Commodore BASIC
1 rem caesar cipher 2 rem rosetta code 10 print chr$(147);chr$(14); 15 input "Enter a key value from 1 to 25";kv 20 if kv<1 or kv>25 then print "Out of range.":goto 15 25 gosub 1000 30 print chr$(147);"Enter a message to translate." 35 print:print "Press CTRL-Z when finished.":print 40 mg$="":gosub 2000 45 print chr$(1...
Give a code snippet in #Commodore_BASIC Task Implement a Caesar cipher, both encoding and decoding. The key is an integer from 1 to 25. This cipher rotates (either towards left or right) the letters of the alphabet (A to Z). The encoding replaces each letter with the 1st to 25th next letter in the alphabet (wra...
christopher/rosetta-code
http://rosettacode.org/wiki/Palindrome_detection
Palindrome detection
A palindrome is a phrase which reads the same backward and forward. Task[edit] Write a function or program that checks whether a given sequence of characters (or, if you prefer, bytes) is a palindrome. For extra credit: Support Unicode characters. Write a second function (possibly as a wrapper to the first) which ...
#ML
ML
fun to_locase s = implode ` map (c_downcase) ` explode s   fun only_alpha s = implode ` filter (fn x = c_alphabetic x) ` explode s   fun is_palin ( h1 :: t1, h2 :: t2, n = 0 ) = true | ( h1 :: t1, h2 :: t2, n ) where ( h1 eql h2 ) = is_palin( t1, t2, n - 1) | ( h1 :: t1, h2 :: t2, n ) = ...
Give a code snippet in #ML A palindrome is a phrase which reads the same backward and forward. Task[edit] Write a function or program that checks whether a given sequence of characters (or, if you prefer, bytes) is a palindrome. For extra credit: Support Unicode characters. Write a second function (possibly as a ...
christopher/rosetta-code
http://rosettacode.org/wiki/Trabb_Pardo%E2%80%93Knuth_algorithm
Trabb Pardo–Knuth algorithm
The TPK algorithm is an early example of a programming chrestomathy. It was used in Donald Knuth and Luis Trabb Pardo's Stanford tech report The Early Development of Programming Languages. The report traces the early history of work in developing computer languages in the 1940s and 1950s, giving several translations of...
#AWK
AWK
  # syntax: GAWK -f TRABB_PARDO-KNUTH_ALGORITHM.AWK BEGIN { printf("enter 11 numbers: ") getline S n = split(S,arr," ") if (n != 11) { printf("%d numbers entered; S/B 11\n",n) exit(1) } for (i=n; i>0; i--) { x = f(arr[i]) printf("f(%s) = %s\n",arr[i],(x>400) ? "too large"...
Give a code snippet in #AWK The TPK algorithm is an early example of a programming chrestomathy. It was used in Donald Knuth and Luis Trabb Pardo's Stanford tech report The Early Development of Programming Languages. The report traces the early history of work in developing computer languages in the 1940s and 1950s, g...
christopher/rosetta-code
http://rosettacode.org/wiki/Increment_a_numerical_string
Increment a numerical string
Task Increment a numerical string.
#Oberon-2
Oberon-2
MODULE addstr;   IMPORT Out, Strings;   VAR str1, str2 : ARRAY 9 OF CHAR; num, pos : INTEGER; carry : BOOLEAN; ch : CHAR;   BEGIN str1 := "9999"; Out.Char ('"'); Out.String (str1); Out.String ('" + 1 = '); num := Strings.Length (str1) - 1;...
Give a code snippet in #Oberon-2 Task Increment a numerical string.
christopher/rosetta-code
http://rosettacode.org/wiki/Address_of_a_variable
Address of a variable
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 |...
#Yorick
Yorick
> foo = 1 > bar = &foo > bar 0x15f42c18 > baz = bar > *baz = 5 > *bar 5 > *baz 5
Give a code snippet in #Yorick 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...
christopher/rosetta-code
http://rosettacode.org/wiki/Sorting_algorithms/Cocktail_sort
Sorting algorithms/Cocktail sort
Sorting Algorithm This is a sorting algorithm.   It may be applied to a set of data in order to sort it.     For comparing various sorts, see compare sorts.   For other sorting algorithms,   see sorting algorithms,   or: O(n logn) sorts Heap sort | Merge sort | Patience sort | Quick sort O(n log2n) sorts Shell Sort ...
#ooRexx
ooRexx
/* Rexx */   placesList = .array~of( - "UK London", "US New York" , "US Boston", "US Washington" - , "UK Washington", "US Birmingham" , "UK Birmingham", "UK Boston" - )   sortedList = cocktailSort(placesList~allItems())   lists = .array~of(placesList, sortedList) loop ln = 1 to lists~items()...
Give a code snippet in #ooRexx Sorting Algorithm This is a sorting algorithm.   It may be applied to a set of data in order to sort it.     For comparing various sorts, see compare sorts.   For other sorting algorithms,   see sorting algorithms,   or: O(n logn) sorts Heap sort | Merge sort | Patience sort | Quick s...
christopher/rosetta-code
http://rosettacode.org/wiki/Zig-zag_matrix
Zig-zag matrix
Task Produce a zig-zag array. A   zig-zag   array is a square arrangement of the first   N2   natural numbers,   where the numbers increase sequentially as you zig-zag along the array's   anti-diagonals. For a graphical representation, see   JPG zigzag   (JPG uses such arrays to encode images). For example, gi...
#PicoLisp
PicoLisp
(load "@lib/simul.l")   (de zigzag (N) (prog1 (grid N N) (let (D '(north west south east .) E '(north east .) This 'a1) (for Val (* N N) (=: val Val) (setq This (or ((cadr D) ((car D) This)) (prog (setq...
Give a code snippet in #PicoLisp Task Produce a zig-zag array. A   zig-zag   array is a square arrangement of the first   N2   natural numbers,   where the numbers increase sequentially as you zig-zag along the array's   anti-diagonals. For a graphical representation, see   JPG zigzag   (JPG uses such arrays to ...
christopher/rosetta-code
http://rosettacode.org/wiki/Formatted_numeric_output
Formatted numeric output
Task Express a number in decimal as a fixed-length string with leading zeros. For example, the number   7.125   could be expressed as   00007.125.
#F.C5.8Drmul.C3.A6
Fōrmulæ
Public Sub Main()   Print Format("7.125", "00000.000")   End
Give a code snippet in #F.C5.8Drmul.C3.A6 Task Express a number in decimal as a fixed-length string with leading zeros. For example, the number   7.125   could be expressed as   00007.125.
christopher/rosetta-code
http://rosettacode.org/wiki/Here_document
Here document
A   here document   (or "heredoc")   is a way of specifying a text block, preserving the line breaks, indentation and other whitespace within the text. Depending on the language being used, a   here document   is constructed using a command followed by "<<" (or some other symbol) followed by a token string. The text ...
#Kotlin
Kotlin
// version 1.1.0   fun main(args: Array<String>) { val ev = "embed variables"   val here = """ This is a raw string literal which does not treat escaped characters (\t, \b, \n, \r, \', \", \\, \$ and \u) specially and can contain new lines, ...
Give a code snippet in #Kotlin A   here document   (or "heredoc")   is a way of specifying a text block, preserving the line breaks, indentation and other whitespace within the text. Depending on the language being used, a   here document   is constructed using a command followed by "<<" (or some other symbol) follow...
christopher/rosetta-code
http://rosettacode.org/wiki/Quine
Quine
A quine is a self-referential program that can, without any external access, output its own source. A   quine   (named after Willard Van Orman Quine)   is also known as:   self-reproducing automata   (1972)   self-replicating program         or   self-replicating computer program   self-reproducing program      ...
#BQN
BQN
•Out 1⌽∾˜18⥊•Repr"•Out 1⌽∾˜18⥊•Repr"
Give a code snippet in #BQN A quine is a self-referential program that can, without any external access, output its own source. A   quine   (named after Willard Van Orman Quine)   is also known as:   self-reproducing automata   (1972)   self-replicating program         or   self-replicating computer program   s...
christopher/rosetta-code
http://rosettacode.org/wiki/Sorting_algorithms/Selection_sort
Sorting algorithms/Selection sort
Sorting Algorithm This is a sorting algorithm.   It may be applied to a set of data in order to sort it.     For comparing various sorts, see compare sorts.   For other sorting algorithms,   see sorting algorithms,   or: O(n logn) sorts Heap sort | Merge sort | Patience sort | Quick sort O(n log2n) sorts Shell Sort ...
#Wren
Wren
var selectionSort = Fn.new { |a| var last = a.count - 1 for (i in 0...last) { var aMin = a[i] var iMin = i for (j in i+1..last) { if (a[j] < aMin) { aMin = a[j] iMin = j } } var t = a[i] a[i] = aMin a...
Give a code snippet in #Wren Sorting Algorithm This is a sorting algorithm.   It may be applied to a set of data in order to sort it.     For comparing various sorts, see compare sorts.   For other sorting algorithms,   see sorting algorithms,   or: O(n logn) sorts Heap sort | Merge sort | Patience sort | Quick sor...
christopher/rosetta-code
http://rosettacode.org/wiki/Visualize_a_tree
Visualize a tree
A tree structure   (i.e. a rooted, connected acyclic graph)   is often used in programming. It's often helpful to visually examine such a structure. There are many ways to represent trees to a reader, such as:   indented text   (à la unix tree command)   nested HTML tables   hierarchical GUI widgets   2D   or ...
#C
C
#include <stdio.h> #include <stdlib.h>   typedef struct stem_t *stem; struct stem_t { const char *str; stem next; };   void tree(int root, stem head) { static const char *sdown = " |", *slast = " `", *snone = " "; struct stem_t col = {0, 0}, *tail;   for (tail = head; tail; tail = tail->next) { printf("%s", ta...
Give a code snippet in #C A tree structure   (i.e. a rooted, connected acyclic graph)   is often used in programming. It's often helpful to visually examine such a structure. There are many ways to represent trees to a reader, such as:   indented text   (à la unix tree command)   nested HTML tables   hierarchi...
christopher/rosetta-code
http://rosettacode.org/wiki/Loops/For_with_a_specified_step
Loops/For with a specified step
Task Demonstrate a   for-loop   where the step-value is greater than one. Related tasks   Loop over multiple arrays simultaneously   Loops/Break   Loops/Continue   Loops/Do-while   Loops/Downward for   Loops/For   Loops/For with a specified step   Loops/Foreach   Loops/Increment loop index within loop b...
#Sather
Sather
i :INT; loop i := for!(1, 50, 2); -- OR -- i := 1.stepto!(50, 2); #OUT + i + "\n"; end;
Give a code snippet in #Sather Task Demonstrate a   for-loop   where the step-value is greater than one. Related tasks   Loop over multiple arrays simultaneously   Loops/Break   Loops/Continue   Loops/Do-while   Loops/Downward for   Loops/For   Loops/For with a specified step   Loops/Foreach   Loops/In...
christopher/rosetta-code
http://rosettacode.org/wiki/Program_termination
Program termination
Task Show the syntax for a complete stoppage of a program inside a   conditional. This includes all threads/processes which are part of your program. Explain the cleanup (or lack thereof) caused by the termination (allocated memory, database connections, open files, object finalizers/destructors, run-on-exit hooks...
#AutoHotkey
AutoHotkey
If (problem) ExitApp
Give a code snippet in #AutoHotkey Task Show the syntax for a complete stoppage of a program inside a   conditional. This includes all threads/processes which are part of your program. Explain the cleanup (or lack thereof) caused by the termination (allocated memory, database connections, open files, object final...
christopher/rosetta-code
http://rosettacode.org/wiki/Check_output_device_is_a_terminal
Check output device is a terminal
Task Demonstrate how to check whether the output device is a terminal or not. Related task   Check input device is a terminal
#Nim
Nim
import terminal   stderr.write if stdout.isatty: "stdout is a terminal\n" else: "stdout is not a terminal\n"
Give a code snippet in #Nim Task Demonstrate how to check whether the output device is a terminal or not. Related task   Check input device is a terminal
christopher/rosetta-code
http://rosettacode.org/wiki/First-class_functions
First-class functions
A language has first-class functions if it can do each of the following without recursively invoking a compiler or interpreter or otherwise metaprogramming: Create new functions from preexisting functions at run-time Store functions in collections Use functions as arguments to other functions Use functions as retu...
#PicoLisp
PicoLisp
(load "@lib/math.l")   (de compose (F G) (curry (F G) (X) (F (G X)) ) )   (de cube (X) (pow X 3.0) )   (de cubeRoot (X) (pow X 0.3333333) )   (mapc '((Fun Inv) (prinl (format ((compose Inv Fun) 0.5) *Scl)) ) '(sin cos cube) '(asin acos cubeRoot) )
Give a code snippet in #PicoLisp A language has first-class functions if it can do each of the following without recursively invoking a compiler or interpreter or otherwise metaprogramming: Create new functions from preexisting functions at run-time Store functions in collections Use functions as arguments to othe...
christopher/rosetta-code
http://rosettacode.org/wiki/Write_float_arrays_to_a_text_file
Write float arrays to a text file
Task Write two equal-sized numerical arrays 'x' and 'y' to a two-column text file named 'filename'. The first column of the file contains values from an 'x'-array with a given 'xprecision', the second -- values from 'y'-array with 'yprecision'. For example, considering: x = {1, 2, 3, 1e11}; y = {1, 1.41421356...
#AWK
AWK
$ awk 'BEGIN{split("1 2 3 1e11",x); > split("1 1.4142135623730951 1.7320508075688772 316227.76601683791",y); > for(i in x)printf("%6g %.5g\n",x[i],y[i])}' 1e+11 3.1623e+05 1 1 2 1.4142 3 1.7321
Give a code snippet in #AWK Task Write two equal-sized numerical arrays 'x' and 'y' to a two-column text file named 'filename'. The first column of the file contains values from an 'x'-array with a given 'xprecision', the second -- values from 'y'-array with 'yprecision'. For example, considering: x = {1, 2, 3,...
christopher/rosetta-code
http://rosettacode.org/wiki/Holidays_related_to_Easter
Holidays related to Easter
Task Calculate the dates of:   Easter   Ascension Thursday   Pentecost   Trinity Sunday   Corpus Christi feast (for Catholic)   All Saints' Sunday (for Orthodox) As an example, calculate for the first year of each century from;   years     400   to   2100 CE   and for   years   2010   to   2020 CE. Note ...
#JavaScript
JavaScript
const Пасха = год => { let дата = (год % 19 * 19 + 15) % 30; дата += (год % 4 * 2 + год % 7 * 4 + 6 * дата + 6) % 7; if (год >= 1918) дата += (год / 100 | 0) - (год / 400 | 0) - 2; return new Date(год, 2, 22 + дата); };   for (let год = 400; год <= 2100; год += год < 2000 ? 100 : год >= 2020 ? 80 : год < 2010 ? 10 ...
Give a code snippet in #JavaScript Task Calculate the dates of:   Easter   Ascension Thursday   Pentecost   Trinity Sunday   Corpus Christi feast (for Catholic)   All Saints' Sunday (for Orthodox) As an example, calculate for the first year of each century from;   years     400   to   2100 CE   and for  ...
christopher/rosetta-code
http://rosettacode.org/wiki/Sequence:_nth_number_with_exactly_n_divisors
Sequence: nth number with exactly n divisors
Calculate the sequence where each term an is the nth that has n divisors. Task Show here, on this page, at least the first 15 terms of the sequence. See also OEIS:A073916 Related tasks Sequence: smallest number greater than previous term with exactly n divisors Sequence: smallest number with exactly n divisors
#C
C
#include <math.h> #include <stdbool.h> #include <stdint.h> #include <stdio.h>   #define LIMIT 15 int smallPrimes[LIMIT];   static void sieve() { int i = 2, j; int p = 5;   smallPrimes[0] = 2; smallPrimes[1] = 3;   while (i < LIMIT) { for (j = 0; j < i; j++) { if (smallPrimes[j] *...
Give a code snippet in #C Calculate the sequence where each term an is the nth that has n divisors. Task Show here, on this page, at least the first 15 terms of the sequence. See also OEIS:A073916 Related tasks Sequence: smallest number greater than previous term with exactly n divisors Sequence: smallest number wit...
christopher/rosetta-code
http://rosettacode.org/wiki/Magic_squares_of_odd_order
Magic squares of odd order
A magic square is an   NxN   square matrix whose numbers (usually integers) consist of consecutive numbers arranged so that the sum of each row and column,   and   both long (main) diagonals are equal to the same sum (which is called the   magic number   or   magic constant). The numbers are usually (but not always) t...
#VBScript
VBScript
  Sub magic_square(n) Dim ms() ReDim ms(n-1,n-1) inc = 0 count = 1 row = 0 col = Int(n/2) Do While count <= n*n ms(row,col) = count count = count + 1 If inc < n-1 Then inc = inc + 1 row = row - 1 col = col + 1 If row >= 0 Then If col > n-1 Then col = 0 End If Else row = n-1 ...
Give a code snippet in #VBScript A magic square is an   NxN   square matrix whose numbers (usually integers) consist of consecutive numbers arranged so that the sum of each row and column,   and   both long (main) diagonals are equal to the same sum (which is called the   magic number   or   magic constant). The numb...
christopher/rosetta-code
http://rosettacode.org/wiki/SHA-1
SHA-1
SHA-1 or SHA1 is a one-way hash function; it computes a 160-bit message digest. SHA-1 often appears in security protocols; for example, many HTTPS websites use RSA with SHA-1 to secure their connections. BitTorrent uses SHA-1 to verify downloads. Git and Mercurial use SHA-1 digests to identify commits. A US government...
#zkl
zkl
$ zkl // run the REPL zkl: var MsgHash=Import("zklMsgHash") MsgHash zkl: MsgHash.SHA1("Rosetta Code") 48c98f7e5a6e736d790ab740dfc3f51a61abe2b5   zkl: var hash=MsgHash.SHA1("Rosetta Code",1,False) // hash once, return hash as bytes Data(20) zkl: hash.bytes() L(72,201,143,126,90,110,115,109,121,10,183,64,223,195,245,26...
Give a code snippet in #zkl SHA-1 or SHA1 is a one-way hash function; it computes a 160-bit message digest. SHA-1 often appears in security protocols; for example, many HTTPS websites use RSA with SHA-1 to secure their connections. BitTorrent uses SHA-1 to verify downloads. Git and Mercurial use SHA-1 digests to ident...
christopher/rosetta-code
http://rosettacode.org/wiki/Van_Eck_sequence
Van Eck sequence
The sequence is generated by following this pseudo-code: A: The first term is zero. Repeatedly apply: If the last term is *new* to the sequence so far then: B: The next term is zero. Otherwise: C: The next term is how far back this last term occured previously. Example Using ...
#F.C5.8Drmul.C3.A6
Fōrmulæ
package main   import "fmt"   func main() { const max = 1000 a := make([]int, max) // all zero by default for n := 0; n < max-1; n++ { for m := n - 1; m >= 0; m-- { if a[m] == a[n] { a[n+1] = n - m break } } } fmt.Println("...
Give a code snippet in #F.C5.8Drmul.C3.A6 The sequence is generated by following this pseudo-code: A: The first term is zero. Repeatedly apply: If the last term is *new* to the sequence so far then: B: The next term is zero. Otherwise: C: The next term is how far back this last ...
christopher/rosetta-code
http://rosettacode.org/wiki/Greatest_element_of_a_list
Greatest element of a list
Task Create a function that returns the maximum value in a provided set of values, where the number of values may not be known until run-time.
#Objeck
Objeck
  values := IntVector->New([4, 1, 42, 5]); values->Max()->PrintLine();  
Give a code snippet in #Objeck Task Create a function that returns the maximum value in a provided set of values, where the number of values may not be known until run-time.
christopher/rosetta-code
http://rosettacode.org/wiki/Compound_data_type
Compound data type
Data Structure This illustrates a data structure, a means of storing data within a program. You may see other such structures in the Data Structures category. Task Create a compound data type: Point(x,y) A compound data type is one that holds multiple independent values. Related task   Enumeration S...
#zkl
zkl
class Point{ var x,y; fcn init(x,y){self.x=x.toFloat(); self.y=y.toFloat(); } fcn toString{ "P(%f,%f)".fmt(x,y) } fcn __opADD(P){} //+: add Point, constant or whatever //... __opEQ == etc } Point(1,2).println() //-->P(1.000000,2.000000)
Give a code snippet in #zkl Data Structure This illustrates a data structure, a means of storing data within a program. You may see other such structures in the Data Structures category. Task Create a compound data type: Point(x,y) A compound data type is one that holds multiple independent values. Rel...
christopher/rosetta-code
http://rosettacode.org/wiki/Smarandache_prime-digital_sequence
Smarandache prime-digital sequence
The Smarandache prime-digital sequence (SPDS for brevity) is the sequence of primes whose digits are themselves prime. For example 257 is an element of this sequence because it is prime itself and its digits: 2, 5 and 7 are also prime. Task Show the first 25 SPDS primes. Show the hundredth SPDS prime. See also ...
#Ring
Ring
  load "stdlib.ring"   see "First 25 Smarandache primes:" + nl + nl   num = 0 limit = 26 limit100 = 100 for n = 1 to 34000 flag = 0 nStr = string(n) for x = 1 to len(nStr) nx = number(nStr[x]) if isprime(n) and isprime(nx) flag = flag + 1 else exit ok ...
Give a code snippet in #Ring The Smarandache prime-digital sequence (SPDS for brevity) is the sequence of primes whose digits are themselves prime. For example 257 is an element of this sequence because it is prime itself and its digits: 2, 5 and 7 are also prime. Task Show the first 25 SPDS primes. Show the hundr...
christopher/rosetta-code
http://rosettacode.org/wiki/Smith_numbers
Smith numbers
Smith numbers are numbers such that the sum of the decimal digits of the integers that make up that number is the same as the sum of the decimal digits of its prime factors excluding 1. By definition, all primes are excluded as they (naturally) satisfy this condition! Smith numbers are also known as   joke   numbers....
#Scala
Scala
object SmithNumbers extends App {   def sumDigits(_n: Int): Int = { var n = _n var sum = 0 while (n > 0) { sum += (n % 10) n /= 10 } sum }   def primeFactors(_n: Int): List[Int] = { var n = _n val result = new collection.mutable.ListBuffer[Int] val i = 2 while (n % ...
Give a code snippet in #Scala Smith numbers are numbers such that the sum of the decimal digits of the integers that make up that number is the same as the sum of the decimal digits of its prime factors excluding 1. By definition, all primes are excluded as they (naturally) satisfy this condition! Smith numbers are ...
christopher/rosetta-code
http://rosettacode.org/wiki/Execute_HQ9%2B
Execute HQ9+
Task Implement a   HQ9+   interpreter or compiler.
#Common_Lisp
Common Lisp
import std.stdio, std.string;   void main(in string[] args) { if (args.length != 2 || args[1].length != args[1].countchars("hHqQ9+")) { writeln("Not valid HQ9+ code."); return; }   ulong accumulator; foreach (immutable c; args[1]) { final switch(c) { case 'Q',...
Give a code snippet in #Common_Lisp Task Implement a   HQ9+   interpreter or compiler.
christopher/rosetta-code
http://rosettacode.org/wiki/Function_prototype
Function prototype
Some languages provide the facility to declare functions and subroutines through the use of function prototyping. Task Demonstrate the methods available for declaring prototypes within the language. The provided solutions should include: An explanation of any placement restrictions for prototype declarations A p...
#Amazing_Hopper
Amazing Hopper
  #!/usr/bin/hopper   // Archivo Hopper #include <hopper.h>   #context-free noargs /* Declare a pseudo-function with no argument */ #synon noargs no arguments #context multiargs /* Declare a pseudo-function with multi arguments */ #proto twoargs(_X_,_Y_) /* Declare a pseudo-function w...
Give a code snippet in #Amazing_Hopper Some languages provide the facility to declare functions and subroutines through the use of function prototyping. Task Demonstrate the methods available for declaring prototypes within the language. The provided solutions should include: An explanation of any placement rest...
christopher/rosetta-code
http://rosettacode.org/wiki/Padovan_n-step_number_sequences
Padovan n-step number sequences
As the Fibonacci sequence expands to the Fibonacci n-step number sequences; We similarly expand the Padovan sequence to form these Padovan n-step number sequences. The Fibonacci-like sequences can be defined like this: For n == 2: start: 1, 1 Recurrence: R(n, x) = R(n, x-1) + R(n, x-2); for n ==...
#Mathematica.2FWolfram_Language
Mathematica/Wolfram Language
ClearAll[Padovan] Padovan[2,tmax_]:=Module[{start,a,m}, start={1,1,1}; start=MapIndexed[a[#2[[1]]]==#1&,start]; RecurrenceTable[{a[m]==a[m-2]+a[m-3]}~Join~start,a, {m,tmax}] ] Padovan[n_,tmax_]:=Module[{start,eq,a,m}, start=Padovan[n-1,n+1]; start=MapIndexed[a[#2[[1]]]==#1&,start]; eq=Range[2,n+1]; eq=Append[st...
Give a code snippet in #Mathematica.2FWolfram_Language As the Fibonacci sequence expands to the Fibonacci n-step number sequences; We similarly expand the Padovan sequence to form these Padovan n-step number sequences. The Fibonacci-like sequences can be defined like this: For n == 2: start: 1, 1 ...
christopher/rosetta-code
http://rosettacode.org/wiki/Draw_a_sphere
Draw a sphere
Task Draw a sphere. The sphere can be represented graphically, or in ASCII art, depending on the language capabilities. Either static or rotational projection is acceptable for this task. Related tasks draw a cuboid draw a rotating cube write language name in 3D ASCII draw a Deathstar
#Clojure
Clojure
  (use 'quil.core)   (def w 500) (def h 400)   (defn setup [] (background 0))   (defn draw [] (push-matrix) (translate 250 200 0) (sphere 100) (pop-matrix))   (defsketch main  :title "sphere"  :setup setup  :size [w h]  :draw draw  :renderer :opengl)  
Give a code snippet in #Clojure Task Draw a sphere. The sphere can be represented graphically, or in ASCII art, depending on the language capabilities. Either static or rotational projection is acceptable for this task. Related tasks draw a cuboid draw a rotating cube write language name in 3D ASCII draw a ...
christopher/rosetta-code
http://rosettacode.org/wiki/Reduced_row_echelon_form
Reduced row echelon form
Reduced row echelon form You are encouraged to solve this task according to the task description, using any language you may know. Task Show how to compute the reduced row echelon form (a.k.a. row canonical form) of a matrix. The matrix can be stored in any datatype that is convenient (for most languages, this wil...
#Octave
Octave
A = [ 1, 2, -1, -4; 2, 3, -1, -11; -2, 0, -3, 22]; refA = rref(A); disp(refA);
Give a code snippet in #Octave Reduced row echelon form You are encouraged to solve this task according to the task description, using any language you may know. Task Show how to compute the reduced row echelon form (a.k.a. row canonical form) of a matrix. The matrix can be stored in any datatype that is convenie...
christopher/rosetta-code
http://rosettacode.org/wiki/Rot-13
Rot-13
Task Implement a   rot-13   function   (or procedure, class, subroutine, or other "callable" object as appropriate to your programming environment). Optionally wrap this function in a utility program   (like tr,   which acts like a common UNIX utility, performing a line-by-line rot-13 encoding of every line of inpu...
#Visual_Basic_.NET
Visual Basic .NET
Module Module1   Private Function rot13(ByVal str As String) As String Dim newChars As Char(), i, j As Integer, original, replacement As String   original = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" replacement = "NOPQRSTUVWXYZABCDEFGHIJKLMnopqrstuvwxyzabcdefghijklm"   newCha...
Give a code snippet in #Visual_Basic_.NET Task Implement a   rot-13   function   (or procedure, class, subroutine, or other "callable" object as appropriate to your programming environment). Optionally wrap this function in a utility program   (like tr,   which acts like a common UNIX utility, performing a line-by...
christopher/rosetta-code
http://rosettacode.org/wiki/24_game/Solve
24 game/Solve
task Write a program that takes four digits, either from user input or by random generation, and computes arithmetic expressions following the rules of the 24 game. Show examples of solutions generated by the program. Related task   Arithmetic Evaluator
#Rust
Rust
#[derive(Clone, Copy, Debug)] enum Operator { Sub, Plus, Mul, Div, }   #[derive(Clone, Debug)] struct Factor { content: String, value: i32, }   fn apply(op: Operator, left: &[Factor], right: &[Factor]) -> Vec<Factor> { let mut ret = Vec::new(); for l in left.iter() { for r in rig...
Give a code snippet in #Rust task Write a program that takes four digits, either from user input or by random generation, and computes arithmetic expressions following the rules of the 24 game. Show examples of solutions generated by the program. Related task   Arithmetic Evaluator
christopher/rosetta-code
http://rosettacode.org/wiki/Logical_operations
Logical operations
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 |...
#M4
M4
define(`logical', `and($1,$2)=eval($1&&$2) or($1,$2)=eval($1||$2) not($1)=eval(!$1)') logical(1,0)
Give a code snippet in #M4 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 Con...
christopher/rosetta-code
http://rosettacode.org/wiki/Rosetta_Code/Count_examples
Rosetta Code/Count examples
task Essentially, count the number of occurrences of =={{header| on each task page. Output: 100 doors: 20 examples. 99 Bottles of Beer: 29 examples. Abstract type: 10 examples. Total: X examples. For a full output, updated periodically, see Rosetta Code/Count examples/Full list. You'll need to use the Media Wiki AP...
#EGL
EGL
package com.eglexamples.client;   import org.eclipse.edt.rui.widgets.*;   handler RosettaCodeHandler type RUIhandler{initialUI =[ui], title = "Rosetta Code Tasks and Counts"}   ui GridLayout{columns = 3, rows = 4, cellPadding = 4, children = [ b1, dg1, l1, l2, l3, l4 ]};   b1 Button{ layoutData = new GridLayout...
Give a code snippet in #EGL task Essentially, count the number of occurrences of =={{header| on each task page. Output: 100 doors: 20 examples. 99 Bottles of Beer: 29 examples. Abstract type: 10 examples. Total: X examples. For a full output, updated periodically, see Rosetta Code/Count examples/Full list. You'll ...
christopher/rosetta-code
http://rosettacode.org/wiki/Percolation/Mean_cluster_density
Percolation/Mean cluster density
Percolation Simulation This is a simulation of aspects of mathematical percolation theory. For other percolation simulations, see Category:Percolation Simulations, or: 1D finite grid simulation Mean run density 2D finite grid simulations Site percolation | Bond percolation | Mean cluster density Let c {\disp...
#Tcl
Tcl
package require Tcl 8.6   proc determineClusters {w h p} { # Construct the grid set grid [lrepeat $h [lrepeat $w 0]] for {set i 0} {$i < $h} {incr i} { for {set j 0} {$j < $w} {incr j} { lset grid $i $j [expr {rand() < $p ? -1 : 0}] } } # Find (and count) the clusters set cl 0 for {se...
Give a code snippet in #Tcl Percolation Simulation This is a simulation of aspects of mathematical percolation theory. For other percolation simulations, see Category:Percolation Simulations, or: 1D finite grid simulation Mean run density 2D finite grid simulations Site percolation | Bond percolation | Mean cluste...
christopher/rosetta-code
http://rosettacode.org/wiki/Comments
Comments
Task Show all ways to include text in a language source file that's completely ignored by the compiler or interpreter. Related tasks   Documentation   Here_document See also   Wikipedia   xkcd (Humor: hand gesture denoting // for "commenting out" people.)
#Logtalk
Logtalk
% single-line comment; extends to the end of the line
Give a code snippet in #Logtalk Task Show all ways to include text in a language source file that's completely ignored by the compiler or interpreter. Related tasks   Documentation   Here_document See also   Wikipedia   xkcd (Humor: hand gesture denoting // for "commenting out" people.)
christopher/rosetta-code
http://rosettacode.org/wiki/Matrix_transposition
Matrix transposition
Transpose an arbitrarily sized rectangular Matrix.
#Octave
Octave
a = [ 1, 1, 1, 1 ; 2, 4, 8, 16 ; 3, 9, 27, 81 ; 4, 16, 64, 256 ; 5, 25, 125, 625 ]; tranposed = a.'; % tranpose ctransp = a'; % conjugate transpose
Give a code snippet in #Octave Transpose an arbitrarily sized rectangular Matrix.
christopher/rosetta-code
http://rosettacode.org/wiki/Strip_a_set_of_characters_from_a_string
Strip a set of characters from a string
Task Create a function that strips a set of characters from a string. The function should take two arguments:   a string to be stripped   a string containing the set of characters to be stripped The returned string should contain the first string, stripped of any characters in the second argument: print str...
#Julia
Julia
stripChar = (s, r) -> replace(s, Regex("[$r]") => "")
Give a code snippet in #Julia Task Create a function that strips a set of characters from a string. The function should take two arguments:   a string to be stripped   a string containing the set of characters to be stripped The returned string should contain the first string, stripped of any characters in t...
christopher/rosetta-code
http://rosettacode.org/wiki/Loops/Increment_loop_index_within_loop_body
Loops/Increment loop index within loop body
Sometimes, one may need   (or want)   a loop which its   iterator   (the index variable)   is modified within the loop body   in addition to the normal incrementation by the   (do)   loop structure index. Goal Demonstrate the best way to accomplish this. Task Write a loop which:   starts the index (variable...
#Haxe
Haxe
using StringTools; import haxe.Int64;   class PrimeNumberLoops { private static var limit = 42;   static function isPrime(i:Int64):Bool { if (i == 2 || i == 3) { return true; } else if (i % 2 == 0 || i % 3 ==0) { return false; } var idx:haxe.Int64 = 5; while (idx * idx <= i) { ...
Give a code snippet in #Haxe Sometimes, one may need   (or want)   a loop which its   iterator   (the index variable)   is modified within the loop body   in addition to the normal incrementation by the   (do)   loop structure index. Goal Demonstrate the best way to accomplish this. Task Write a loop which: ...
christopher/rosetta-code
http://rosettacode.org/wiki/Hickerson_series_of_almost_integers
Hickerson series of almost integers
The following function,   due to D. Hickerson,   is said to generate "Almost integers" by the "Almost Integer" page of Wolfram MathWorld,   (December 31 2013).   (See formula numbered   51.) The function is:           h ( n ) = n ! 2 ( ln ⁡ 2 ) n + 1 {\displaystyle h(n)={\operatorname {n} ! \ove...
#Rust
Rust
  use decimal::d128; use factorial::Factorial;   fn hickerson(n: u64) -> d128 { d128::from(n.factorial()) / (d128!(2) * (d128!(2).ln().pow(d128::from(n + 1)))) }   // Some details on floating-points numbers can be found at https://cheats.rs/#basic-types fn main() { for i in 1..18 { let h = hickerson(i);...
Give a code snippet in #Rust The following function,   due to D. Hickerson,   is said to generate "Almost integers" by the "Almost Integer" page of Wolfram MathWorld,   (December 31 2013).   (See formula numbered   51.) The function is:           h ( n ) = n ! 2 ( ln ⁡ 2 ) n + 1 {\displaystyle ...
christopher/rosetta-code
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
#Oforth
Oforth
System cmd("pause")
Give a code snippet in #Oforth Task Run either the   ls   system command   (dir   on Windows),   or the   pause   system command. Related task Get system command output
christopher/rosetta-code
http://rosettacode.org/wiki/Terminal_control/Unicode_output
Terminal control/Unicode output
The task is to check that the terminal supports Unicode output, before outputting a Unicode character. If the terminal supports Unicode, then the terminal should output a Unicode delta (U+25b3). If the terminal does not support Unicode, then an appropriate error should be raised. Note that it is permissible to use sys...
#jq
jq
def has_unicode_support: def utf: if . == null then false else contains("UTF") or contains("utf") end; env.LC_ALL | if utf then true elif . != null and . != "" then false elif env.LC_CTYPE | utf then true else env.LANG | utf end ;   def task: if has_unicode_support then "\u25b3" else error("HW...
Give a code snippet in #jq The task is to check that the terminal supports Unicode output, before outputting a Unicode character. If the terminal supports Unicode, then the terminal should output a Unicode delta (U+25b3). If the terminal does not support Unicode, then an appropriate error should be raised. Note that ...
christopher/rosetta-code
http://rosettacode.org/wiki/Arithmetic/Integer
Arithmetic/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 |...
#Liberty_BASIC
Liberty BASIC
  input "Enter the first integer: "; first input "Enter the second integer: "; second   print "The sum is " ; first + second print "The difference is " ; first -second print "The product is " ; first *second if second <>0 then print "The integer quotient is " ; int( first /second); " (rounds towards 0)" else print "Di...
Give a code snippet in #Liberty_BASIC 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 Ope...
christopher/rosetta-code
http://rosettacode.org/wiki/Function_composition
Function composition
Task Create a function, compose,   whose two arguments   f   and   g,   are both functions with one argument. The result of compose is to be a function of one argument, (lets call the argument   x),   which works like applying function   f   to the result of applying function   g   to   x. Example compose...
#Tcl
Tcl
package require Tcl 8.5 namespace path {::tcl::mathfunc}   proc compose {f g} { list apply [list {f g x} {{*}$f [{*}$g $x]}] $f $g] }   set sin_asin [compose sin asin] {*}$sin_asin 0.5 ;# ==> 0.5 {*}[compose abs int] -3.14 ;# ==> 3
Give a code snippet in #Tcl Task Create a function, compose,   whose two arguments   f   and   g,   are both functions with one argument. The result of compose is to be a function of one argument, (lets call the argument   x),   which works like applying function   f   to the result of applying function   g   ...
christopher/rosetta-code
http://rosettacode.org/wiki/Non-decimal_radices/Convert
Non-decimal radices/Convert
Number base conversion is when you express a stored integer in an integer base, such as in octal (base 8) or binary (base 2). It also is involved when you take a string representing a number in a given base and convert it to the stored integer form. Normally, a stored integer is in binary, but that's typically invisibl...
#Java
Java
public static long backToTen(String num, int oldBase){ return Long.parseLong(num, oldBase); //takes both uppercase and lowercase letters }   public static String tenToBase(long num, int newBase){ return Long.toString(num, newBase);//add .toUpperCase() for capital letters }
Give a code snippet in #Java Number base conversion is when you express a stored integer in an integer base, such as in octal (base 8) or binary (base 2). It also is involved when you take a string representing a number in a given base and convert it to the stored integer form. Normally, a stored integer is in binary,...
christopher/rosetta-code
http://rosettacode.org/wiki/Colour_pinstripe/Display
Colour pinstripe/Display
The task is to create 1 pixel wide coloured vertical pinstripes with a sufficient number of pinstripes to span the entire width of the graphics display. The pinstripes should either follow the system palette sequence,   or a sequence that includes: black,   red,   green,   blue,   magenta,   cyan,   yellow,   and  ...
#AutoHotkey
AutoHotkey
h := A_ScreenHeight w := A_ScreenWidth pToken := gdip_Startup() hdc := CreateCompatibleDC() hbm := CreateDIBSection(w, h) obm := SelectObject(hdc, hbm) G := Gdip_GraphicsFromHDC(hdc)   OnExit, Exit   Gui -Caption +E0x80000 +LastFound +OwnDialogs +Owner +AlwaysOnTop Gui Show, NA hwnd := WinExist()   colors := [0xFF00000...
Give a code snippet in #AutoHotkey The task is to create 1 pixel wide coloured vertical pinstripes with a sufficient number of pinstripes to span the entire width of the graphics display. The pinstripes should either follow the system palette sequence,   or a sequence that includes: black,   red,   green,   blue, ...
christopher/rosetta-code
http://rosettacode.org/wiki/Matrix_multiplication
Matrix multiplication
Task Multiply two matrices together. They can be of any dimensions, so long as the number of columns of the first matrix is equal to the number of rows of the second matrix.
#FreeBASIC
FreeBASIC
type Matrix dim as double m( any , any ) declare constructor ( ) declare constructor ( byval x as uinteger , byval y as uinteger ) end type   constructor Matrix ( ) end constructor   constructor Matrix ( byval x as uinteger , byval y as uinteger ) redim this.m( x - 1 , y - 1 ) end constructor   operator...
Give a code snippet in #FreeBASIC Task Multiply two matrices together. They can be of any dimensions, so long as the number of columns of the first matrix is equal to the number of rows of the second matrix.
christopher/rosetta-code
http://rosettacode.org/wiki/Echo_server
Echo server
Create a network service that sits on TCP port 12321, which accepts connections on that port, and which echoes complete lines (using a carriage-return/line-feed sequence as line separator) back to clients. No error handling is required. For the purposes of testing, it is only necessary to support connections from local...
#Java
Java
import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.io.OutputStreamWriter; import java.io.PrintWriter; import java.net.ServerSocket; import java.net.Socket; import java.nio.charset.Charset; import java.nio.charset.StandardCharsets;   public class EchoServer {   p...
Give a code snippet in #Java Create a network service that sits on TCP port 12321, which accepts connections on that port, and which echoes complete lines (using a carriage-return/line-feed sequence as line separator) back to clients. No error handling is required. For the purposes of testing, it is only necessary to ...
christopher/rosetta-code
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....
#Tcl
Tcl
package require Tcl 8.5   # A function to select a random character from an argument string proc tcl::mathfunc::randchar s { string index $s [expr {int([string length $s]*rand())}] }   # Set up the initial variables set target "METHINKS IT IS LIKE A WEASEL" set charset "ABCDEFGHIJKLMNOPQRSTUVWXYZ " set parent [subs...
Give a code snippet in #Tcl 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 a...
christopher/rosetta-code
http://rosettacode.org/wiki/Averages/Arithmetic_mean
Averages/Arithmetic mean
Task[edit] Write a program to find the mean (arithmetic average) of a numeric vector. In case of a zero-length input, since the mean of an empty set of numbers is ill-defined, the program may choose to behave in any way it deems appropriate, though if the programming language has an established convention for conveyin...
#Elena
Elena
import extensions;   extension op { average() { real sum := 0; int count := 0;   var enumerator := self.enumerator();   while (enumerator.next()) { sum += enumerator.get(); count += 1; };   ^ sum / count } }   public program() {...
Give a code snippet in #Elena Task[edit] Write a program to find the mean (arithmetic average) of a numeric vector. In case of a zero-length input, since the mean of an empty set of numbers is ill-defined, the program may choose to behave in any way it deems appropriate, though if the programming language has an esta...
christopher/rosetta-code
http://rosettacode.org/wiki/Hash_from_two_arrays
Hash from two arrays
Task Using two Arrays of equal length, create a Hash object where the elements from one array (the keys) are linked to the elements of the other (the values) Related task   Associative arrays/Creation
#Pop11
Pop11
vars keys = { 1 a b c}; vars vals = { 2 3 valb valc}; vars i; ;;; Create hash table vars ht = newmapping([], 500, 0, true); ;;; Loop over input arrays (vectors) for i from 1 to length(keys) do vals(i) -> ht(keys(i)); endfor;
Give a code snippet in #Pop11 Task Using two Arrays of equal length, create a Hash object where the elements from one array (the keys) are linked to the elements of the other (the values) Related task   Associative arrays/Creation
christopher/rosetta-code
http://rosettacode.org/wiki/Koch_curve
Koch curve
Draw a Koch curve. See details: Koch curve
#Quackery
Quackery
[ $ "turtleduck.qky" loadfile ] now!   [ $ "" swap witheach [ nested quackery join ] ] is expand ( $ --> $ )   [ $ "FRFLLFRF" ] is F ( $ --> $ )   [ $ "L" ] is L ( $ --> $ )   [ $ "R" ] is R ( $ --> $ )   $ "FLLFLLF"  ...
Give a code snippet in #Quackery Draw a Koch curve. See details: Koch curve
christopher/rosetta-code
http://rosettacode.org/wiki/CSV_to_HTML_translation
CSV to HTML translation
Consider a simplified CSV format where all rows are separated by a newline and all columns are separated by commas. No commas are allowed as field data, but the data may contain other characters and character sequences that would normally be   escaped   when converted to HTML Task Create a function that takes a st...
#C.23
C#
  using System; using System.Collections.Generic; using System.Linq; using System.Net;   class Program { private static string ConvertCsvToHtmlTable(string csvText) { //split the CSV, assume no commas or line breaks in text List<List<string>> splitString = new List<List<s...
Give a code snippet in #C.23 Consider a simplified CSV format where all rows are separated by a newline and all columns are separated by commas. No commas are allowed as field data, but the data may contain other characters and character sequences that would normally be   escaped   when converted to HTML Task Cre...
christopher/rosetta-code
http://rosettacode.org/wiki/Literals/Integer
Literals/Integer
Some programming languages have ways of expressing integer literals in bases other than the normal base ten. Task Show how integer literals can be expressed in as many bases as your language allows. Note:   this should not involve the calling of any functions/methods, but should be interpreted by the compiler or...
#Eiffel
Eiffel
  123 -- decimal -1_2_3 -- decimal 0x7b -- hexadecimal 0c173 -- octal 0b111_1011 -- binary  
Give a code snippet in #Eiffel Some programming languages have ways of expressing integer literals in bases other than the normal base ten. Task Show how integer literals can be expressed in as many bases as your language allows. Note:   this should not involve the calling of any functions/methods, but should b...
christopher/rosetta-code
http://rosettacode.org/wiki/Loops/Downward_for
Loops/Downward for
Task Write a   for   loop which writes a countdown from   10   to   0. Related tasks   Loop over multiple arrays simultaneously   Loops/Break   Loops/Continue   Loops/Do-while   Loops/Downward for   Loops/For   Loops/For with a specified step   Loops/Foreach   Loops/Increment loop index within loop body...
#EchoLisp
EchoLisp
  (for ((longtemps-je-me-suis-couché-de-bonne-heure (in-range 10 -1 -1))) (write longtemps-je-me-suis-couché-de-bonne-heure)) → 10 9 8 7 6 5 4 3 2 1 0  
Give a code snippet in #EchoLisp Task Write a   for   loop which writes a countdown from   10   to   0. Related tasks   Loop over multiple arrays simultaneously   Loops/Break   Loops/Continue   Loops/Do-while   Loops/Downward for   Loops/For   Loops/For with a specified step   Loops/Foreach   Loops/Inc...
christopher/rosetta-code
http://rosettacode.org/wiki/Assertions
Assertions
Assertions are a way of breaking out of code when there is an error or an unexpected input. Some languages throw exceptions and some treat it as a break point. Task Show an assertion in your language by asserting that an integer variable is equal to 42.
#Eiffel
Eiffel
class MAIN creation main feature main is local test: TEST; do create test;   io.read_integer; test.assert(io.last_integer); end end
Give a code snippet in #Eiffel Assertions are a way of breaking out of code when there is an error or an unexpected input. Some languages throw exceptions and some treat it as a break point. Task Show an assertion in your language by asserting that an integer variable is equal to 42.
christopher/rosetta-code
http://rosettacode.org/wiki/Trabb_Pardo%E2%80%93Knuth_algorithm
Trabb Pardo–Knuth algorithm
The TPK algorithm is an early example of a programming chrestomathy. It was used in Donald Knuth and Luis Trabb Pardo's Stanford tech report The Early Development of Programming Languages. The report traces the early history of work in developing computer languages in the 1940s and 1950s, giving several translations of...
#PARI.2FGP
PARI/GP
{ print("11 numbers: "); v=vector(11, n, eval(input())); v=apply(x->x=sqrt(abs(x))+5*x^3;if(x>400,"overflow",x), v); vector(11, i, v[12-i]) }
Give a code snippet in #PARI.2FGP The TPK algorithm is an early example of a programming chrestomathy. It was used in Donald Knuth and Luis Trabb Pardo's Stanford tech report The Early Development of Programming Languages. The report traces the early history of work in developing computer languages in the 1940s and 19...
christopher/rosetta-code
http://rosettacode.org/wiki/Knuth_shuffle
Knuth shuffle
The   Knuth shuffle   (a.k.a. the Fisher-Yates shuffle)   is an algorithm for randomly shuffling the elements of an array. Task Implement the Knuth shuffle for an integer array (or, if possible, an array of any type). Specification Given an array items with indices ranging from 0 to last, the algorithm can be d...
#C.2B.2B
C++
#include <cstdlib> #include <algorithm> #include <iterator>   template<typename RandomAccessIterator> void knuthShuffle(RandomAccessIterator begin, RandomAccessIterator end) { for(unsigned int n = end - begin - 1; n >= 1; --n) { unsigned int k = rand() % (n + 1); if(k != n) { std::iter_swap(begin + k, b...
Give a code snippet in #C.2B.2B The   Knuth shuffle   (a.k.a. the Fisher-Yates shuffle)   is an algorithm for randomly shuffling the elements of an array. Task Implement the Knuth shuffle for an integer array (or, if possible, an array of any type). Specification Given an array items with indices ranging from ...
christopher/rosetta-code
http://rosettacode.org/wiki/Man_or_boy_test
Man or boy test
Man or boy test You are encouraged to solve this task according to the task description, using any language you may know. Background: The man or boy test was proposed by computer scientist Donald Knuth as a means of evaluating implementations of the ALGOL 60 programming language. The aim of the test was to distinguis...
#Racket
Racket
#lang racket   (define (A k x1 x2 x3 x4 x5) (define (B) (set! k (- k 1)) (A k B x1 x2 x3 x4)) (if (<= k 0) (+ (x4) (x5)) (B)))   (A 10 (lambda () 1) (lambda () -1) (lambda () -1) (lambda () 1) (lambda () 0))
Give a code snippet in #Racket Man or boy test You are encouraged to solve this task according to the task description, using any language you may know. Background: The man or boy test was proposed by computer scientist Donald Knuth as a means of evaluating implementations of the ALGOL 60 programming language. The a...
christopher/rosetta-code
http://rosettacode.org/wiki/Random_numbers
Random numbers
Task Generate a collection filled with   1000   normally distributed random (or pseudo-random) numbers with a mean of   1.0   and a   standard deviation   of   0.5 Many libraries only generate uniformly distributed random numbers. If so, you may use one of these algorithms. Related task   Standard deviation
#Wren
Wren
import "random" for Random   var rand = Random.new()   var randNormal = Fn.new { (-2 * rand.float().log).sqrt * (2 * Num.pi * rand.float()).cos }   var stdDev = Fn.new { |a, m| var c = a.count return ((a.reduce(0) { |acc, x| acc + x*x } - m*m*c) / c).sqrt }   var n = 1000 var numbers = List.filled(n, 0) var mu ...
Give a code snippet in #Wren Task Generate a collection filled with   1000   normally distributed random (or pseudo-random) numbers with a mean of   1.0   and a   standard deviation   of   0.5 Many libraries only generate uniformly distributed random numbers. If so, you may use one of these algorithms. Related ...
christopher/rosetta-code
http://rosettacode.org/wiki/Metronome
Metronome
The task is to implement a   metronome. The metronome should be capable of producing high and low audio beats, accompanied by a visual beat indicator, and the beat pattern and tempo should be configurable. For the purpose of this task, it is acceptable to play sound files for production of the beat notes, and an ext...
#Delphi
Delphi
  program Metronome;   {$APPTYPE CONSOLE}   uses Winapi.Windows, System.SysUtils;   procedure StartMetronome(bpm: double; measure: Integer); var counter: Integer; begin counter := 0; while True do begin Sleep(Trunc(1000 * (60.0 / bpm))); inc(counter); if counter mod measure = 0 then writel...
Give a code snippet in #Delphi The task is to implement a   metronome. The metronome should be capable of producing high and low audio beats, accompanied by a visual beat indicator, and the beat pattern and tempo should be configurable. For the purpose of this task, it is acceptable to play sound files for producti...
christopher/rosetta-code
http://rosettacode.org/wiki/Time_a_function
Time a function
Task Write a program which uses a timer (with the least granularity available on your system) to time how long a function takes to execute. Whenever possible, use methods which measure only the processing time used by the current process; instead of the difference in system time between start and finish, which could ...
#BaCon
BaCon
' Time a function SUB timed() SLEEP 7000 END SUB   st = TIMER timed() et = TIMER PRINT st, ", ", et
Give a code snippet in #BaCon Task Write a program which uses a timer (with the least granularity available on your system) to time how long a function takes to execute. Whenever possible, use methods which measure only the processing time used by the current process; instead of the difference in system time between...
christopher/rosetta-code
http://rosettacode.org/wiki/Loop_over_multiple_arrays_simultaneously
Loop over multiple arrays simultaneously
Task Loop over multiple arrays   (or lists or tuples or whatever they're called in your language)   and display the   i th   element of each. Use your language's   "for each"   loop if it has one, otherwise iterate through the collection in order with some other loop. For this example, loop over the arrays: ...
#Axe
Axe
'a'→{L₁} 'b'→{L₁+1} 'c'→{L₁+2} 'A'→{L₂} 'B'→{L₂+1} 'C'→{L₂+2} 1→{L₃} 2→{L₃+1} 3→{L₃+2} For(I,0,2) Disp {L₁+I}►Char,{L₂+I}►Char,{L₃+I}►Dec,i End
Give a code snippet in #Axe Task Loop over multiple arrays   (or lists or tuples or whatever they're called in your language)   and display the   i th   element of each. Use your language's   "for each"   loop if it has one, otherwise iterate through the collection in order with some other loop. For this exampl...
christopher/rosetta-code
http://rosettacode.org/wiki/Character_codes
Character codes
Task Given a character value in your language, print its code   (could be ASCII code, Unicode code, or whatever your language uses). Example The character   'a'   (lowercase letter A)   has a code of 97 in ASCII   (as well as Unicode, as ASCII forms the beginning of Unicode). Conversely, given a code, print out...
#Zoea
Zoea
  program: character_codes input: a output: 97  
Give a code snippet in #Zoea Task Given a character value in your language, print its code   (could be ASCII code, Unicode code, or whatever your language uses). Example The character   'a'   (lowercase letter A)   has a code of 97 in ASCII   (as well as Unicode, as ASCII forms the beginning of Unicode). Conve...
christopher/rosetta-code
http://rosettacode.org/wiki/Mandelbrot_set
Mandelbrot set
Mandelbrot set You are encouraged to solve this task according to the task description, using any language you may know. Task Generate and draw the Mandelbrot set. Note that there are many algorithms to draw Mandelbrot set and there are many functions which generate it .
#B
B
main() { auto cx,cy,x,y,x2,y2; auto iter;   auto xmin,xmax,ymin,ymax,maxiter,dx,dy;   xmin = -8601; xmax = 2867; ymin = -4915; ymax = 4915;   maxiter = 32;   dx = (xmax-xmin)/79; dy = (ymax-ymin)/24;   cy=ymin; while( cy<=ymax ) { cx=xmin; while( cx<=xmax ) { x = 0; y = 0; ...
Give a code snippet in #B Mandelbrot set You are encouraged to solve this task according to the task description, using any language you may know. Task Generate and draw the Mandelbrot set. Note that there are many algorithms to draw Mandelbrot set and there are many functions which generate it .
christopher/rosetta-code
http://rosettacode.org/wiki/Mad_Libs
Mad Libs
This page uses content from Wikipedia. The original article was at Mad Libs. The list of authors can be seen in the page history. As with Rosetta Code, the text of Wikipedia is available under the GNU FDL. (See links for details on variance) Mad Libs is a phrasal template word game where one player prompts another...
#VBScript
VBScript
Function mad_libs(s) Do If InStr(1,s,"<") <> 0 Then start_position = InStr(1,s,"<") + 1 end_position = InStr(1,s,">") parse_string = Mid(s,start_position,end_position-start_position) WScript.StdOut.Write parse_string & "? " input_string = WScript.S...
Give a code snippet in #VBScript This page uses content from Wikipedia. The original article was at Mad Libs. The list of authors can be seen in the page history. As with Rosetta Code, the text of Wikipedia is available under the GNU FDL. (See links for details on variance) Mad Libs is a phrasal template word gam...
christopher/rosetta-code
http://rosettacode.org/wiki/Factors_of_a_Mersenne_number
Factors of a Mersenne number
A Mersenne number is a number in the form of 2P-1. If P is prime, the Mersenne number may be a Mersenne prime (if P is not prime, the Mersenne number is also not prime). In the search for Mersenne prime numbers it is advantageous to eliminate exponents by finding a small factor before starting a, potentially lengthy,...
#Erlang
Erlang
  -module(mersene2). -export([prime/1,modpow/3,mf/1]).   mf(P) -> merseneFactor(P,math:sqrt(math:pow(2,P)-1),2).   merseneFactor(P,Limit,Acc) when Acc >= Limit -> io:write("None found"); ...
Give a code snippet in #Erlang A Mersenne number is a number in the form of 2P-1. If P is prime, the Mersenne number may be a Mersenne prime (if P is not prime, the Mersenne number is also not prime). In the search for Mersenne prime numbers it is advantageous to eliminate exponents by finding a small factor before ...
christopher/rosetta-code
http://rosettacode.org/wiki/Y_combinator
Y combinator
In strict functional programming and the lambda calculus, functions (lambda expressions) don't have state and are only allowed to refer to arguments of enclosing functions. This rules out the usual definition of a recursive function wherein a function is associated with the state of a variable and this variable's stat...
#FreeBASIC
FreeBASIC
Function Y(f As String) As String Y = f End Function   Function fib(n As Long) As Long Dim As Long n1 = 0, n2 = 1, k, sum For k = 1 To Abs(n) sum = n1 + n2 n1 = n2 n2 = sum Next k Return Iif(n < 0, (n1 * ((-1) ^ ((-n)+1))), n1) End Function   Function fac(n As Long) As Long ...
Give a code snippet in #FreeBASIC In strict functional programming and the lambda calculus, functions (lambda expressions) don't have state and are only allowed to refer to arguments of enclosing functions. This rules out the usual definition of a recursive function wherein a function is associated with the state of ...
christopher/rosetta-code
http://rosettacode.org/wiki/Loops/Foreach
Loops/Foreach
Loop through and print each element in a collection in order. Use your language's "for each" loop if it has one, otherwise iterate through the collection in order with some other loop. Related tasks   Loop over multiple arrays simultaneously   Loops/Break   Loops/Continue   Loops/Do-while   Loops/Downward for...
#langur
langur
for .i in [1, 2, 3] { writeln .i }   val .abc = "abc"   for .i in .abc { writeln .i }   for .i of .abc { writeln .abc[.i] }   for .i in .abc { writeln cp2s .i }
Give a code snippet in #langur Loop through and print each element in a collection in order. Use your language's "for each" loop if it has one, otherwise iterate through the collection in order with some other loop. Related tasks   Loop over multiple arrays simultaneously   Loops/Break   Loops/Continue   Loop...
christopher/rosetta-code
http://rosettacode.org/wiki/Simple_windowed_application
Simple windowed application
Task Create a window that has:   a label that says   "There have been no clicks yet"   a button that says   "click me" Upon clicking the button with the mouse, the label should change and show the number of times the button has been clicked.
#Scala
Scala
import scala.swing.{ BorderPanel, Button, Label, MainFrame, SimpleSwingApplication } import scala.swing.event.ButtonClicked   object SimpleApp extends SimpleSwingApplication { def top = new MainFrame { contents = new BorderPanel { var nClicks = 0   val (button, label) = (new Button { text = "click me"...
Give a code snippet in #Scala Task Create a window that has:   a label that says   "There have been no clicks yet"   a button that says   "click me" Upon clicking the button with the mouse, the label should change and show the number of times the button has been clicked.
christopher/rosetta-code
http://rosettacode.org/wiki/Wilson_primes_of_order_n
Wilson primes of order n
Definition A Wilson prime of order n is a prime number   p   such that   p2   exactly divides: (n − 1)! × (p − n)! − (− 1)n If   n   is   1,   the latter formula reduces to the more familiar:   (p - n)! + 1   where the only known examples for   p   are   5,   13,   and   563. Task Calculate and show on thi...
#BASIC
BASIC
function isPrime(v) if v <= 1 then return False for i = 2 To int(sqr(v)) if v % i = 0 then return False next i return True end function   function isWilson(n, p) if p < n then return false prod = 1 p2 = p*p #p^2 for i = 1 to n-1 prod = (prod*i) mod p2 next i for i = 1 to p-n prod = (prod*i) mod p2 next...
Give a code snippet in #BASIC Definition A Wilson prime of order n is a prime number   p   such that   p2   exactly divides: (n − 1)! × (p − n)! − (− 1)n If   n   is   1,   the latter formula reduces to the more familiar:   (p - n)! + 1   where the only known examples for   p   are   5,   13,   and   563. ...
christopher/rosetta-code
http://rosettacode.org/wiki/String_length
String length
Task Find the character and byte length of a string. This means encodings like UTF-8 need to be handled properly, as there is not necessarily a one-to-one relationship between bytes and characters. By character, we mean an individual Unicode code point, not a user-visible grapheme containing combining characters. F...
#Clojure
Clojure
(def utf-8-octet-length #(-> % (.getBytes "UTF-8") count)) (map utf-8-octet-length ["møøse" "𝔘𝔫𝔦𝔠𝔬𝔡𝔢" "J\u0332o\u0332s\u0332e\u0301\u0332"]) ; (7 28 14)   (def utf-16-octet-length (comp (partial * 2) count)) (map utf-16-octet-length ["møøse" "𝔘𝔫𝔦𝔠𝔬𝔡𝔢" "J\u0332o\u0332s\u0332e\u0301\u0332"]) ; (10 28 18)  ...
Give a code snippet in #Clojure Task Find the character and byte length of a string. This means encodings like UTF-8 need to be handled properly, as there is not necessarily a one-to-one relationship between bytes and characters. By character, we mean an individual Unicode code point, not a user-visible grapheme co...
christopher/rosetta-code
http://rosettacode.org/wiki/RPG_attributes_generator
RPG attributes generator
RPG   =   Role Playing Game. You're running a tabletop RPG, and your players are creating characters. Each character has six core attributes: strength, dexterity, constitution, intelligence, wisdom, and charisma. One way of generating values for these attributes is to roll four, 6-sided dice (d6) and sum the three...
#Julia
Julia
roll_skip_lowest(dice, sides) = (r = rand(collect(1:sides), dice); sum(r) - minimum(r))   function rollRPGtoon() attributes = zeros(Int, 6) attsum = 0 gte15 = 0   while attsum < 75 || gte15 < 2 for i in 1:6 attributes[i] = roll_skip_lowest(4, 6) end attsum = sum(attri...
Give a code snippet in #Julia RPG   =   Role Playing Game. You're running a tabletop RPG, and your players are creating characters. Each character has six core attributes: strength, dexterity, constitution, intelligence, wisdom, and charisma. One way of generating values for these attributes is to roll four, 6-si...
christopher/rosetta-code
http://rosettacode.org/wiki/Literals/Floating_point
Literals/Floating point
Programming languages have different ways of expressing floating-point literals. Task Show how floating-point literals can be expressed in your language: decimal or other bases, exponential notation, and any other special features. You may want to include a regular expression or BNF/ABNF/EBNF defining allowable fo...
#Sidef
Sidef
say 1.234; say .1234; say 1234e-5; say 12.34e5;
Give a code snippet in #Sidef Programming languages have different ways of expressing floating-point literals. Task Show how floating-point literals can be expressed in your language: decimal or other bases, exponential notation, and any other special features. You may want to include a regular expression or BNF/...
christopher/rosetta-code
http://rosettacode.org/wiki/Continued_fraction
Continued fraction
continued fraction Mathworld a 0 + b 1 a 1 + b 2 a 2 + b 3 a 3 + ⋱ {\displaystyle a_{0}+{\cfrac {b_{1}}{a_{1}+{\cfrac {b_{2}}{a_{2}+{\cfrac {b_{3}}{a_{3}+\ddots }}}}}}} The task is to write a program which generates su...
#ATS
ATS
#include "share/atspre_staload.hats" // (* ****** ****** *) // (* ** a coefficient function creates double values from in paramters *) typedef coeff_f = int -> double // (* ** a continued fraction is described by a record of two coefficent ** functions a and b *) typedef frac = @{a= coeff_f, b= coeff_f} // (* ****** **...
Give a code snippet in #ATS continued fraction Mathworld a 0 + b 1 a 1 + b 2 a 2 + b 3 a 3 + ⋱ {\displaystyle a_{0}+{\cfrac {b_{1}}{a_{1}+{\cfrac {b_{2}}{a_{2}+{\cfrac {b_{3}}{a_{3}+\ddots }}}}}}} The task is to write...
christopher/rosetta-code
http://rosettacode.org/wiki/Introspection
Introspection
Task verify the version/revision of your currently running (compiler/interpreter/byte-compiler/runtime environment/whatever your language uses) and exit if it is too old. check whether the variable "bloop" exists and whether the math-function "abs()" is available and if yes compute abs(bloop). Extra credit Repor...
#PowerShell
PowerShell
# version is found in $PSVersionTable if ($PSVersionTable['PSVersion'] -lt '2.0') { exit }   if ((Test-Path Variable:bloop) -and ([Math]::Abs)) { [Math]::Abs($bloop) }   # find integer variables and their sum Get-Variable -Scope global ` | Where-Object { $_.Value -is [int] } ` | Measure-Object -Sum Valu...
Give a code snippet in #PowerShell Task verify the version/revision of your currently running (compiler/interpreter/byte-compiler/runtime environment/whatever your language uses) and exit if it is too old. check whether the variable "bloop" exists and whether the math-function "abs()" is available and if yes comput...
christopher/rosetta-code
http://rosettacode.org/wiki/Dining_philosophers
Dining philosophers
The dining philosophers problem illustrates non-composability of low-level synchronization primitives like semaphores. It is a modification of a problem posed by Edsger Dijkstra. Five philosophers, Aristotle, Kant, Spinoza, Marx, and Russell (the tasks) spend their time thinking and eating spaghetti. They eat at a rou...
#C.2B.2B
C++
#include <algorithm> #include <array> #include <chrono> #include <iostream> #include <mutex> #include <random> #include <string> #include <string_view> #include <thread>   const int timeScale = 42; // scale factor for the philosophers task duration   void Message(std::string_view message) { // thread safe printing...
Give a code snippet in #C.2B.2B The dining philosophers problem illustrates non-composability of low-level synchronization primitives like semaphores. It is a modification of a problem posed by Edsger Dijkstra. Five philosophers, Aristotle, Kant, Spinoza, Marx, and Russell (the tasks) spend their time thinking and ea...
christopher/rosetta-code
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 iterat...
#AmigaE
AmigaE
PROC fact(x) IS IF x>=2 THEN x*fact(x-1) ELSE 1   PROC main() WriteF('5! = \d\n', fact(5)) ENDPROC
Give a code snippet in #AmigaE 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 ...
christopher/rosetta-code
http://rosettacode.org/wiki/Terminal_control/Ringing_the_terminal_bell
Terminal control/Ringing the terminal bell
Task Make the terminal running the program ring its "bell". On modern terminal emulators, this may be done by playing some other sound which might or might not be configurable, or by flashing the title bar or inverting the colors of the screen, but was classically a physical bell within the terminal.   It is usua...
#Lasso
Lasso
stdoutnl('\a')
Give a code snippet in #Lasso Task Make the terminal running the program ring its "bell". On modern terminal emulators, this may be done by playing some other sound which might or might not be configurable, or by flashing the title bar or inverting the colors of the screen, but was classically a physical bell wi...
christopher/rosetta-code
http://rosettacode.org/wiki/Babbage_problem
Babbage problem
Charles Babbage, looking ahead to the sorts of problems his Analytical Engine would be able to solve, gave this example: What is the smallest positive integer whose square ends in the digits 269,696? — Babbage, letter to Lord Bowden, 1837; see Hollingdale and Tootill, Electronic Computers, second edition, 1970, p....
#VAX_Assembly
VAX Assembly
  36 35 34 33 32 31 00000008'010E0000' 0000 1 result: .ascid "123456"  ;output buffer 0000 000E 2 retlen: .word 0  ;$fao_s bytes written 4C 55 21 00000018'010E0000' 0010 3 format: .ascid "!UL"  ;unsigned decimal...
Give a code snippet in #VAX_Assembly Charles Babbage, looking ahead to the sorts of problems his Analytical Engine would be able to solve, gave this example: What is the smallest positive integer whose square ends in the digits 269,696? — Babbage, letter to Lord Bowden, 1837; see Hollingdale and Tootill, Electron...
christopher/rosetta-code
http://rosettacode.org/wiki/User_input/Text
User input/Text
User input/Text is part of Short Circuit's Console Program Basics selection. Task Input a string and the integer   75000   from the text console. See also: User input/Graphical
#Vedit_macro_language
Vedit macro language
Get_Input(1, "Enter a string: ") #2 = Get_Num("Enter a number: ")
Give a code snippet in #Vedit_macro_language User input/Text is part of Short Circuit's Console Program Basics selection. Task Input a string and the integer   75000   from the text console. See also: User input/Graphical
christopher/rosetta-code
http://rosettacode.org/wiki/Literals/Integer
Literals/Integer
Some programming languages have ways of expressing integer literals in bases other than the normal base ten. Task Show how integer literals can be expressed in as many bases as your language allows. Note:   this should not involve the calling of any functions/methods, but should be interpreted by the compiler or...
#R
R
0x2d7==727 # TRUE identical(0x2d7, 727) # TRUE is.numeric(727) # TRUE is.integer(727) # FALSE is.integer(727L) # TRUE is.numeric(0x2d7) # TRUE is.integer(0x2d7) # FALSE is.integer(0x2d7L) # TRUE
Give a code snippet in #R Some programming languages have ways of expressing integer literals in bases other than the normal base ten. Task Show how integer literals can be expressed in as many bases as your language allows. Note:   this should not involve the calling of any functions/methods, but should be int...
christopher/rosetta-code
http://rosettacode.org/wiki/Percentage_difference_between_images
Percentage difference between images
basic bitmap storage Useful for comparing two JPEG images saved with a different compression ratios. You can use these pictures for testing (use the full-size version of each): 50% quality JPEG 100% quality JPEG link to full size 50% image link to full size 100% image The expected difference for these two...
#Lua
Lua
Bitmap.loadPPM = function(self, filename) local fp = io.open( filename, "rb" ) if fp == nil then return false end local head, width, height, depth, tail = fp:read("*line", "*number", "*number", "*number", "*line") self.width, self.height = width, height self:alloc() self:clear( {0,0,0} ) for y = 1, se...
Give a code snippet in #Lua basic bitmap storage Useful for comparing two JPEG images saved with a different compression ratios. You can use these pictures for testing (use the full-size version of each): 50% quality JPEG 100% quality JPEG link to full size 50% image link to full size 100% image The expe...
christopher/rosetta-code
http://rosettacode.org/wiki/Assertions
Assertions
Assertions are a way of breaking out of code when there is an error or an unexpected input. Some languages throw exceptions and some treat it as a break point. Task Show an assertion in your language by asserting that an integer variable is equal to 42.
#PARI.2FGP
PARI/GP
#include <assert.h> #include <pari/pari.h>   void test() { GEN a; // ... input or change a here   assert(equalis(a, 42)); /* Aborts program if a is not 42, unless the NDEBUG macro was defined */ }
Give a code snippet in #PARI.2FGP Assertions are a way of breaking out of code when there is an error or an unexpected input. Some languages throw exceptions and some treat it as a break point. Task Show an assertion in your language by asserting that an integer variable is equal to 42.
christopher/rosetta-code
http://rosettacode.org/wiki/Text_processing/Max_licenses_in_use
Text processing/Max licenses in use
A company currently pays a fixed sum for the use of a particular licensed software package.   In determining if it has a good deal it decides to calculate its maximum use of the software from its license management log file. Assume the software's licensing daemon faithfully records a checkout event when a copy of the ...
#PureBasic
PureBasic
OpenConsole()   If ReadFile(0, OpenFileRequester("Text processing/3","mlijobs.txt","All files",1)) While Not Eof(0) currline$=ReadString(0) If StringField(currline$,2," ")="OUT" counter+1 Else counter-1 EndIf If counter>max max=counter maxtime$=StringField(currline$,4,"...
Give a code snippet in #PureBasic A company currently pays a fixed sum for the use of a particular licensed software package.   In determining if it has a good deal it decides to calculate its maximum use of the software from its license management log file. Assume the software's licensing daemon faithfully records a...
christopher/rosetta-code
http://rosettacode.org/wiki/Yin_and_yang
Yin and yang
One well-known symbol of the philosophy of duality known as yin and yang is the taijitu. Task   Create a function that, given a parameter representing size, generates such a symbol scaled to the requested size.   Generate and display the symbol for two different (small) sizes.
#Plain_English
Plain English
To run: Start up. Clear the screen to the gray color. Draw the Taijitu symbol 4 inches wide at the screen's center. Put the screen's center into a spot. Move the spot 4 inches right. Draw the Taijitu symbol 2 inches wide at the spot. Refresh the screen. Wait for the escape key. Shut down.   To draw the Taijitu symbol s...
Give a code snippet in #Plain_English One well-known symbol of the philosophy of duality known as yin and yang is the taijitu. Task   Create a function that, given a parameter representing size, generates such a symbol scaled to the requested size.   Generate and display the symbol for two different (small) size...
christopher/rosetta-code
http://rosettacode.org/wiki/Averages/Median
Averages/Median
Task[edit] Write a program to find the   median   value of a vector of floating-point numbers. The program need not handle the case where the vector is empty, but must handle the case where there are an even number of elements.   In that case, return the average of the two middle values. There are several approaches ...
#Ada
Ada
with Ada.Text_IO, Ada.Float_Text_IO;   procedure FindMedian is   f: array(1..10) of float := ( 4.4, 2.3, -1.7, 7.5, 6.6, 0.0, 1.9, 8.2, 9.3, 4.5 ); min_idx: integer; min_val, median_val, swap: float;   begin for i in f'range loop min_idx := i; min_val := f(i); for j in i+1 .. f'l...
Give a code snippet in #Ada Task[edit] Write a program to find the   median   value of a vector of floating-point numbers. The program need not handle the case where the vector is empty, but must handle the case where there are an even number of elements.   In that case, return the average of the two middle values. ...
christopher/rosetta-code
http://rosettacode.org/wiki/List_comprehensions
List comprehensions
A list comprehension is a special syntax in some programming languages to describe lists. It is similar to the way mathematicians describe sets, with a set comprehension, hence the name. Some attributes of a list comprehension are: They should be distinct from (nested) for loops and the use of map and filter functio...
#Clojure
Clojure
(defn pythagorean-triples [n] (for [x (range 1 (inc n)) y (range x (inc n)) z (range y (inc n)) :when (= (+ (* x x) (* y y)) (* z z))] [x y z]))
Give a code snippet in #Clojure A list comprehension is a special syntax in some programming languages to describe lists. It is similar to the way mathematicians describe sets, with a set comprehension, hence the name. Some attributes of a list comprehension are: They should be distinct from (nested) for loops and ...
christopher/rosetta-code
http://rosettacode.org/wiki/Repeat_a_string
Repeat a string
Take a string and repeat it some number of times. Example: repeat("ha", 5)   =>   "hahahahaha" If there is a simpler/more efficient way to repeat a single “character” (i.e. creating a string filled with a certain character), you might want to show that as well (i.e. repeat-char("*", 5) => "*****"). Other tasks re...
#Go
Go
fmt.Println(strings.Repeat("ha", 5)) // ==> "hahahahaha"
Give a code snippet in #Go Take a string and repeat it some number of times. Example: repeat("ha", 5)   =>   "hahahahaha" If there is a simpler/more efficient way to repeat a single “character” (i.e. creating a string filled with a certain character), you might want to show that as well (i.e. repeat-char("*", 5) => ...
christopher/rosetta-code
http://rosettacode.org/wiki/Copy_stdin_to_stdout
Copy stdin to stdout
Create an executable file that copies stdin to stdout, or else a script that does so through the invocation of an interpreter at the command line.
#Ada
Ada
with Ada.Text_IO;   procedure Copy_Stdin_To_Stdout is use Ada.Text_IO; C : Character; begin while not End_Of_File loop Get_Immediate (C); Put (C); end loop; end Copy_Stdin_To_Stdout;
Give a code snippet in #Ada Create an executable file that copies stdin to stdout, or else a script that does so through the invocation of an interpreter at the command line.
christopher/rosetta-code
http://rosettacode.org/wiki/Keyboard_input/Keypress_check
Keyboard input/Keypress check
Determine if a key has been pressed and store this in a variable. If no key has been pressed, the program should continue without waiting.
#C.23
C#
string chr = string.Empty; if(Console.KeyAvailable) chr = Console.ReadKey().Key.ToString();
Give a code snippet in #C.23 Determine if a key has been pressed and store this in a variable. If no key has been pressed, the program should continue without waiting.
christopher/rosetta-code
http://rosettacode.org/wiki/Filter
Filter
Task Select certain elements from an Array into a new Array in a generic way. To demonstrate, select all even numbers from an Array. As an option, give a second solution which filters destructively, by modifying the original Array rather than creating a new Array.
#Scheme
Scheme
  (define filter (lambda (fn lst) (let iter ((lst lst) (result '())) (if (null? lst) (reverse result) (let ((item (car lst)) (rest (cdr lst))) (if (fn item) (iter rest (cons item result)) (iter rest result)))))))  
Give a code snippet in #Scheme Task Select certain elements from an Array into a new Array in a generic way. To demonstrate, select all even numbers from an Array. As an option, give a second solution which filters destructively, by modifying the original Array rather than creating a new Array.
christopher/rosetta-code
http://rosettacode.org/wiki/Arithmetic_evaluation
Arithmetic evaluation
Create a program which parses and evaluates arithmetic expressions. Requirements An abstract-syntax tree (AST) for the expression must be created from parsing the input. The AST must be used in evaluation, also, so the input may not be directly evaluated (e.g. by calling eval or a similar language feature.) The ...
#D
D
import std.stdio, std.string, std.ascii, std.conv, std.array, std.exception, std.traits;   struct Stack(T) { T[] data; alias data this; void push(T top) pure nothrow @safe { data ~= top; }   T pop(bool discard = true)() pure @nogc @safe { immutable static exc = new immutable(Exception)("Sta...
Give a code snippet in #D Create a program which parses and evaluates arithmetic expressions. Requirements An abstract-syntax tree (AST) for the expression must be created from parsing the input. The AST must be used in evaluation, also, so the input may not be directly evaluated (e.g. by calling eval or a simila...
christopher/rosetta-code
http://rosettacode.org/wiki/Literals/Integer
Literals/Integer
Some programming languages have ways of expressing integer literals in bases other than the normal base ten. Task Show how integer literals can be expressed in as many bases as your language allows. Note:   this should not involve the calling of any functions/methods, but should be interpreted by the compiler or...
#zkl
zkl
123, 0d1_000 0x123, 0x12|34 0b1111|0000
Give a code snippet in #zkl Some programming languages have ways of expressing integer literals in bases other than the normal base ten. Task Show how integer literals can be expressed in as many bases as your language allows. Note:   this should not involve the calling of any functions/methods, but should be i...
christopher/rosetta-code
http://rosettacode.org/wiki/Hello_world/Graphical
Hello world/Graphical
Task Display the string       Goodbye, World!       on a GUI object   (alert box, plain window, text area, etc.). Related task   Hello world/Text
#Just_Basic
Just Basic
  print "Goodbye, World!" 'Prints in the upper left corner of the default text window: mainwin, a window with scroll bars.  
Give a code snippet in #Just_Basic Task Display the string       Goodbye, World!       on a GUI object   (alert box, plain window, text area, etc.). Related task   Hello world/Text
christopher/rosetta-code
http://rosettacode.org/wiki/Break_OO_privacy
Break OO privacy
Show how to access private or protected members of a class in an object-oriented language from outside an instance of the class, without calling non-private or non-protected members of the class as a proxy. The intent is to show how a debugger, serializer, or other meta-programming tool might access information that is...
#Python
Python
>>> class MyClassName: __private = 123 non_private = __private * 2     >>> mine = MyClassName() >>> mine.non_private 246 >>> mine.__private Traceback (most recent call last): File "<pyshell#23>", line 1, in <module> mine.__private AttributeError: 'MyClassName' object has no attribute '__private' >>> mine._MyCla...
Give a code snippet in #Python Show how to access private or protected members of a class in an object-oriented language from outside an instance of the class, without calling non-private or non-protected members of the class as a proxy. The intent is to show how a debugger, serializer, or other meta-programming tool ...
christopher/rosetta-code
http://rosettacode.org/wiki/Abbreviations,_automatic
Abbreviations, automatic
The use of   abbreviations   (also sometimes called synonyms, nicknames, AKAs, or aliases)   can be an easy way to add flexibility when specifying or using commands, sub─commands, options, etc. It would make a list of words easier to maintain   (as words are added, changed, and/or deleted)   if the minimum abbrevia...
#Scala
Scala
name := "Abbreviations-automatic" scalaVersion := "2.13.0" version := "0.1"   homepage := Some(url("http://rosettacode.org/wiki/Abbreviations,_automatic#Scala"))   libraryDependencies += "com.lihaoyi" %% "os-lib" % "0.3.0"
Give a code snippet in #Scala The use of   abbreviations   (also sometimes called synonyms, nicknames, AKAs, or aliases)   can be an easy way to add flexibility when specifying or using commands, sub─commands, options, etc. It would make a list of words easier to maintain   (as words are added, changed, and/or del...
christopher/rosetta-code
http://rosettacode.org/wiki/File_size
File size
Verify the size of a file called     input.txt     for a file in the current working directory, and another one in the file system root.
#Perl
Perl
my $size1 = -s 'input.txt'; my $size2 = -s '/input.txt';
Give a code snippet in #Perl Verify the size of a file called     input.txt     for a file in the current working directory, and another one in the file system root.
christopher/rosetta-code