Loops/Break: Difference between revisions

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return 0;
return 0;
}</lang>
}</lang>


=={{header|C++}}==
<lang cpp>#include <iostream>
#include <ctime>
#include <cstdlib>

int main()
{
srand(time(0));
while(true)
{
int a = 0 + rand() % 19;
std::cout << a << std::endl;
if (a == 10)
break;
int b = 0 + rand() % 19;
std::cout << b << std::endl;
}
return 0;
}</lang>

=={{header|C sharp|C#}}==
=={{header|C sharp|C#}}==
<lang csharp>class Program
<lang csharp>class Program

Revision as of 14:04, 13 November 2010

Task
Loops/Break
You are encouraged to solve this task according to the task description, using any language you may know.

Show a loop which prints random numbers (each number newly generated each loop) from 0 to 19 (inclusive). If a number is 10, stop the loop after printing it, and do not generate any further numbers. Otherwise, generate and print a second random number before restarting the loop. If the number 10 is never generated as the first number in a loop, loop forever.

6502 Assembly

Code is called as a subroutine (i.e. JSR LoopBreakSub). Specific OS/hardware routines for generating random numbers and printing are left unimplemented. <lang 6502asm>LoopBreakSub: PHA ;push accumulator onto stack


BreakLoop: JSR GenerateRandomNum ;routine not implemented ;generates random number and puts in memory location RandomNumber

LDA RandomNumber JSR DisplayAccumulator ;routine not implemented CMP #10 BEQ Break JSR GenerateRandomNum LDA RandomNumber JSR DisplayAccumulator JMP BreakLoop

Break: PLA ;restore accumulator from stack RTS ;return from subroutine</lang>

Ada

<lang Ada>with Ada.Text_IO; use Ada.Text_IO; with Ada.Numerics.Discrete_Random;

procedure Test_Loop_Break is 

  type Value_Type is range 1..20;
  package Random_Values is new Ada.Numerics.Discrete_Random (Value_Type);
  use Random_Values;
  Dice : Generator;
  A, B : Value_Type;

begin 

  loop
     A := Random (Dice);
     Put_Line (Value_Type'Image (A));
     exit when A = 10;
     B := Random (Dice);
     Put_Line (Value_Type'Image (B));
  end loop;

end Test_Loop_Break;</lang>

ALGOL 68

Translation of: C

- note: This specimen retains the original C coding style.

Works with: ALGOL 68 version Standard - no extensions to language used
Works with: ELLA ALGOL 68 version Any (with appropriate job cards)

<lang algol68>main: ( 

   INT a, b;
   INT seed := 4; # chosen by a fair dice roll, guaranteed to be random c.f. http://xkcd.com/221/ #
   # first random; #
   WHILE
       a := ENTIER (next random(seed) * 20);
       print((a));
 # WHILE # NOT (a = 10) DO
       b := ENTIER (next random(seed) * 20);
       print((b, new line))
   OD;
   print(new line)

)</lang> Sample output: 

        +13          +6
         +1          +8
        +13          +2
         +1         +12
         +0         +12
        +14          +8
         +9          +2
        +19         +13
         +0          +4
         +8         +14
        +17          +7
        +11          +9
         +7          +8
         +2          +1
        +11          +2
        +13         +18
         +3          +7
        +11         +17
         +4         +13
        +16         +12
        +19         +17
         +9          +7
         +8          +5
         +4          +8
         +7          +5
         +0         +18
         +8         +13
         +7          +4
        +10

AutoHotkey

<lang AutoHotkey>Loop { 

 Random, var, 0, 19
 output = %output%`n%var%
 If (var = 10)
   Break
 Random, var, 0, 19
 output = %output%`n%var%

} MsgBox % output</lang>

Bash

<lang bash>while true; do 

 echo $((a=RANDOM%20))
 [ $a -eq 10 ] && break
 echo $((b=RANDOM%20))

done</lang>

BASIC

Works with: QuickBasic version 4.5

<lang qbasic>do 

   a = int(rnd * 20)
   print a
   if a = 10 then exit loop 'EXIT FOR works the same inside FOR loops
   b = int(rnd * 20)
   print b

loop</lang>

C

<lang c>#include <stdlib.h>

  1. include <time.h>
  2. include <stdio.h>

int main() { 

   int a, b;

   srand(time(NULL));
   while (1) {
       a = rand() % 20; /* not exactly uniformly distributed, but doesn't matter */
       printf("%d\n", a);
       if (a == 10) break;
       b = rand() % 20; /* not exactly uniformly distributed, but doesn't matter */
       printf("%d\n", b);
   }
   return 0;

}</lang>


C++

<lang cpp>#include <iostream>

  1. include <ctime>
  2. include <cstdlib>

int main() { 

   srand(time(0));
   while(true)
   {
   	int a = 0 + rand() % 19;
   	std::cout << a << std::endl;
   	if (a == 10)
   		break;
   	int b = 0 + rand() % 19;
   	std::cout << b << std::endl;
   }
   return 0;

}</lang>

C#

<lang csharp>class Program { 

   static void Main(string[] args)
   {
       Random random = new Random();
       while (true)
       {
           int a = random.Next(20);
           Console.WriteLine(a);
           if (a == 10)
               break;
           int b = random.Next(20)
           Console.WriteLine(b);
       }
          
       Console.ReadLine();
   }

}</lang>

Chef

"Liquify" is now depreciated in favor of "Liquefy", but my interpreter/compiler (Acme::Chef) works only with "Liquify" so that's how I'm leaving it. At least it'll work no matter which version you use.

<lang Chef>Healthy Vita-Sauce Loop - Broken.

Makes a whole lot of sauce for two people.

Ingredients. 0 g Vitamin A 1 g Vitamin B 2 g Vitamin C 3 g Vitamin D 4 g Vitamin E 5 g Vitamin F 6 g Vitamin G 7 g Vitamin H 8 g Vitamin I 9 g Vitamin J 10 g Vitamin K 11 g Vitamin L 12 g Vitamin M 13 g Vitamin N 14 g Vitamin O 15 g Vitamin P 16 g Vitamin Q 17 g Vitamin R 18 g Vitamin S 19 g Vitamin T 20 g Vitamin U 21 g Vitamin V 22 g Vitamin W 32 g Vitamin X 24 g Vitamin Y 25 g Vitamin Z

Method. Liquify Vitamin X. Put Vitamin N into 1st mixing bowl. Fold Vitamin Y into 1st mixing bowl. Liquify Vitamin Y. Clean 1st mixing bowl. Put Vitamin K into 1st mixing bowl. Fold Vitamin Z into 1st mixing bowl. Liquify Vitamin Z. Clean 1st mixing bowl. Put Vitamin Y into 4th mixing bowl. Put Vitamin Z into 4th mixing bowl. Pour contents of the 4th mixing bowl into the 2nd baking dish. Put Vitamin A into 2nd mixing bowl. Put Vitamin B into 2nd mixing bowl. Put Vitamin C into 2nd mixing bowl. Put Vitamin D into 2nd mixing bowl. Put Vitamin E into 2nd mixing bowl. Put Vitamin F into 2nd mixing bowl. Put Vitamin G into 2nd mixing bowl. Put Vitamin H into 2nd mixing bowl. Put Vitamin I into 2nd mixing bowl. Put Vitamin J into 2nd mixing bowl. Put Vitamin K into 2nd mixing bowl. Put Vitamin L into 2nd mixing bowl. Put Vitamin M into 2nd mixing bowl. Put Vitamin N into 2nd mixing bowl. Put Vitamin O into 2nd mixing bowl. Put Vitamin P into 2nd mixing bowl. Put Vitamin Q into 2nd mixing bowl. Put Vitamin R into 2nd mixing bowl. Put Vitamin S into 2nd mixing bowl. Put Vitamin T into 2nd mixing bowl. Verb the Vitamin V. Mix the 2nd mixing bowl well. Fold Vitamin U into 2nd mixing bowl. Put Vitamin U into 3rd mixing bowl. Remove Vitamin K from 3rd mixing bowl. Fold Vitamin V into 3rd mixing bowl. Put Vitamin X into 1st mixing bowl. Put Vitamin V into 1st mixing bowl. Verb until verbed. Pour contents of the 1st mixing bowl into the 1st baking dish.

Serves 2.</lang>

Clojure

<lang lisp>(loop [[a b & more] (repeatedly #(rand-int 20))] 

 (println a)
 (when-not (= 10 a) 
   (println b) 
   (recur more)))</lang>

Common Lisp

<lang lisp>(loop 

   (setq a (random 20))
   (print a)
   (if (= a 10)
       (return))
   (setq b (random 20))
   (print b))</lang>

D

Using Mersenne twister;

Library: Tango

<lang D>import tango.io.Stdout; import tango.math.random.Twister;

void main() { 

   alias Twister.instance r;
   uint x;

   while (~1) {
       x = r.natural(20);
       Stdout (x) (" ");
       if (x == 10) break;
       Stdout (r.natural(20)).newline;
   }

}</lang>

E

<lang e>while (true) { 

   def a := entropy.nextInt(20)
   print(a)
   if (a == 10) {
       println()
       break
   }
   println(" ", entropy.nextInt(20))

}</lang>

Factor

Using with-return: <lang factor>[ 

   [ 20 random [ . ] [ 10 = [ return ] when ] bi 20 random . t ] loop

] with-return</lang>

Idiomatic Factor: <lang factor>[ 20 random [ . ] [ 10 = not ] bi 20 random . ] loop</lang>

Forth

<lang forth>include random.fs

main
 begin  20 random dup . 10 <>
 while  20 random .
 repeat ;

\ use LEAVE to break out of a counted loop

main
 100 0 do
   i random dup .
   10 = if leave then
   i random .
 loop ;</lang>

Fortran

Works with: Fortran version 90 and later

<lang fortran>program Example 

 implicit none

 real :: r
 integer :: a, b

 do
    call random_number(r)
    a = int(r * 20)
    write(*,*) a
    if (a == 10) exit
    call random_number(r)
    b = int(r * 20)
    write(*,*) b
 end do

end program Example</lang>

Go

<lang go>package main import "fmt" import "rand" import "time"

func main() { 

 rand.Seed(time.Nanoseconds())
 for {
   a := rand.Intn(20)
   fmt.Println(a)
   if a == 10 { break }
   b := rand.Intn(20)
   fmt.Println(b)
 }

}</lang>

Haskell

<lang haskell>import Control.Monad import System.Random

loopBreak n k = do 

 r <- randomRIO (0,n)
 print r
 unless (r==k) $ do
   print =<< randomRIO (0,n)
   loopBreak n k</lang>

Use: <lang haskell>loopBreak 19 10</lang>

HicEst

<lang hicest>1 DO i = 1, 1E20 ! "forever" 

    a = INT( RAN(10, 10) )
    WRITE(name) a
    IF( a == 10) GOTO 10
    b = INT( RAN(10, 10) )
    WRITE(name) b
  ENDDO

10 

END</lang>

Icon and Unicon

Icon

<lang Icon>procedure main() 

   while 10 ~= writes(?20-1) do write(", ",?20-1)

end</lang> Notes:

  • For any positive integer i, ?i produces a value j where 1 <= j <= i
  • Although this can be written with a break (e.g. repeat expression & break), there is no need to actually use one. (And it's ugly).
  • Programmers new to Icon/Unicon need to understand that just about everything returns values including comparison operators, I/O functions like write/writes.
  • This program will perform similarly but not identically under Icon and Unicon because the random operator ?i behaves differently. While both produce pseudo-random numbers a different generator is used. Also, the sequence produced by Icon begins with the same seed value and is repeatable whereas the sequence produced by Unicon does not. One way to force Icon to use different random sequences on each call would be to add the line <lang Icon>&random := integer(map("smhSMH","Hh:Mm:Ss",&clock))</lang> at the start of the main procedure to set the random number seed based on the time of day.

Unicon

This Icon solution works in Unicon. A solution that uses Unicon extensions has not been provided.

J

<lang j>loopexample=: verb define 

 while. 1 do.
   smoutput n=. ?20
   if. 10=n do. return. end.
   smoutput ?20
 end.

)</lang>

Java

<lang java>import java.util.Random;

Random rand = new Random(); while(true){ 

   int a = rand.nextInt(20);
   System.out.println(a);
   if(a == 10) break;
   int b = rand.nextInt(20);
   System.out.println(b);

}</lang>

JavaScript

<lang javascript>for (;;) { 

 var a = Math.floor(Math.random() * 20);
 print(a);
 if (a == 10) 
   break;
 a = Math.floor(Math.random() * 20);
 print(a);

}</lang> The print() function is available in the Rhino JavaScript shell.

Lisaac

<lang Lisaac>Section Header

+ name := TEST_LOOP_BREAK;

Section Public

- main <- ( 

 + a, b : INTEGER;

 `srand(time(NULL))`;
 {
   a := `rand()`:INTEGER % 20; // not exactly uniformly distributed, but doesn't matter
   a.print;
   '\n'.print;
   a == 10
 }.until_do {
   b := `rand()`:INTEGER % 20; // not exactly uniformly distributed, but doesn't matter
   b.print;
   '\n'.print;
 }

);</lang>

Lua

<lang lua>repeat 

 k = math.random(19)
 print(k)
 if k == 10 then break end
 print(math.random(19)

until false</lang>

M4

<lang M4>define(`randSeed',141592653)dnl define(`setRand', 

  `define(`randSeed',ifelse(eval($1<10000),1,`eval(20000-$1)',`$1'))')dnl

define(`rand_t',`eval(randSeed^(randSeed>>13))')dnl define(`random', 

  `define(`randSeed',eval((rand_t^(rand_t<<18))&0x7fffffff))randSeed')dnl

dnl define(`loopbreak',`define(`a',eval(random%20))`a='a ifelse(a,10,`',`define(`b',eval(random%20))`b='b loopbreak')')dnl dnl loopbreak</lang>

Output: 

a=17
b=3
a=0
b=15
a=10

Modula-3

<lang modula3>MODULE Break EXPORTS Main;

IMPORT IO, Fmt, Random;

VAR a,b: INTEGER;

BEGIN 

 WITH rand = NEW(Random.Default).init() DO
   LOOP
     a := rand.integer(min := 0, max := 19);
     IO.Put(Fmt.Int(a) & "\n");
     IF a = 10 THEN EXIT END;
     b := rand.integer(min := 0, max := 19);
     IO.Put(Fmt.Int(b) & "\n");
   END;
 END;

END Break.</lang>

MOO

<lang moo>while (1) 

 a = random(20) - 1;
 player:tell(a);
 if (a == 10)
   break;
 endif
 b = random(20) - 1;
 player:tell(b);

endwhile</lang>

MUMPS

<lang MUMPS>BREAKLOOP 

NEW A,B
SET A=""
FOR  Q:A=10  DO
.SET A=$RANDOM(20)
.WRITE !,A
.Q:A=10
.SET B=$RANDOM(20)
.WRITE ?6,B
KILL A,B
QUIT
;A denser version that doesn't require two tests
NEW A,B 
FOR  SET A=$RANDOM(20) WRITE !,A QUIT:A=10  SET B=$RANDOM(20) WRITE ?6,B
KILL A,B QUIT</lang>

Output:

USER>D BREAKLOOP^ROSETTA
 
5     3
9     13
3     12
9     19
16    4
11    17
18    2
4     18
10
USER>D BREAKLOOP+11^ROSETTA
 
6     13
15    3
0     8
8     18
7     13
15    10
15    13
10

Objeck

<lang objeck> while(true) { 

 a := (Float->Random() * 20.0)->As(Int);
 a->PrintLine();
 if(a = 10) { 
   break;
 };
 a := (Float->Random() * 20.0)->As(Int);
 a->PrintLine();

} </lang>

OCaml

<lang ocaml># Random.self_init();; - : unit = ()

  1. while true do
   let a = Random.int 20 in
   print_int a;
   print_newline();
   if a = 10 then raise Exit;
   let b = Random.int 20 in
   print_int b;
   print_newline()
 done;;

15 18 2 13 10 Exception: Pervasives.Exit.</lang>

Octave

<lang octave>while(1) 

 a = floor(unifrnd(0,20, 1));
 disp(a)
 if ( a == 10 )
   break
 endif
 b = floor(unifrnd(0,20, 1));
 disp(b)

endwhile</lang>

Oz

We can implement this either with recursion or with a special type of the for-loop. Both can be considered idiomatic. <lang oz>for break:Break do 

  R = {OS.rand} mod 20

in 

  {Show R}
  if R == 10 then {Break}
  else {Show {OS.rand} mod 20}
  end

end</lang>

PARI/GP

<lang>while(1, 

 t=random(20);
 print(t);
 if(t==10, break);
 print(random(20))

)</lang>

Perl

<lang perl>while (1) { 

   my $a = int(rand(20));
   print "$a\n";
   if ($a == 10) {
       last;
   }
   my $b = int(rand(20));
   print "$b\n";

}</lang>

Perl 6

Works with: Rakudo version #21 "Seattle"

<lang perl6>loop { 

   say my $n = (0..19).pick;
   last if $n == 10;
   say (0..19).pick;

}</lang>

PHP

<lang php>while (true) { 

   $a = rand(0,19);
   echo "$a\n";
   if ($a == 10)
       break;
   $b = rand(0,19);
   echo "$b\n";

}</lang>

PicoLisp

Literally: <lang PicoLisp>(use R 

  (loop
     (println (setq R (rand 1 19)))
     (T (= 10 R))
     (println (rand 1 19)) ) )</lang>

Shorter: <lang PicoLisp>(until (= 10 (println (rand 1 19))) 

  (println (rand 1 19)) )</lang>

PL/I

<lang PL/I> do forever; 

  k = random()*19;
  put (k);
  if k = 10 then leave;
  k = random()*19;
  put skip list (k);

end; </lang>

Pike

<lang pike>int main(){ 

  while(1){
     int a = random(20);
     write(a + "\n");
     if(a == 10){
        break;
     }
     int b = random(20);
     write(b + "\n");
  }

}</lang>

PowerShell

<lang powershell>$r = New-Object Random for () { 

   $n = $r.Next(20)
   Write-Host $n
   if ($n -eq 10) {
       break
   }
   Write-Host $r.Next(20)

}</lang>

PureBasic

<lang PureBasic>If OpenConsole() 

 Repeat
   a = Random(19)
   PrintN(Str(a))
   If a = 10
     Break
   EndIf 
   b = Random(19)
   PrintN(Str(b))
   PrintN("")
 ForEver

 Print(#CRLF$ + #CRLF$ + "Press ENTER to exit")
 Input()
 CloseConsole()

EndIf</lang>

Python

<lang python>import random

while True: 

   a = random.randrange(20)
   print a
   if a == 10:
       break
   b = random.randrange(20)
   print b</lang>

R

Works with: R version 2.8.1

<lang R>sample0to19 <- function() sample(0L:19L, 1,replace=TRUE) repeat { 

 result1 <- sample0to19()
 if (result1 == 10L)
 {
   print(result1)
   break
 }
 result2 <- sample0to19()
 cat(result1, result2, "\n")

}</lang>

REBOL

<lang REBOL>REBOL [ Title: "Loop/Break" Author: oofoe Date: 2009-12-19 URL: http://rosettacode.org/wiki/Loop/Break ]

random/seed 1 ; Make repeatable.

random/seed now ; Uncomment for 'true' randomness.

r20: does [(random 20) - 1]

forever [ prin x: r20 if 10 = x [break] print rejoin [" " r20] ] print ""</lang>

Output: 

14 11
19 15
6 11
12 11
3 14
10

REXX

<lang rexx>do forever 

 a = random(19)
 say a
 if a = 10 then leave
 b = random(19)
 say b

end</lang>


Ruby

<lang ruby>loop do 

   a = rand(20)
   puts a
   if a == 10
       break
   end
   b = rand(20)
   puts b

end</lang>

Sather

<lang sather>-- help class for random number sequence class RANDOM is 

 attr seed:INT;

 create(seed:INT):SAME is
   res:RANDOM := new;
   res.seed := seed;
   return res;
 end;
 -- this code is taken from rand's man (C)
 next:INT is
   seed := seed * 1103515245 + 12345;
   return (seed/65536) % 32768;
 end;

end;

class MAIN is 

 main is
   a, b :INT;
   rnd:RANDOM := #(1);
   loop
     a := rnd.next % 20;
     #OUT + a + "\n";
     if a = 10 then break!; end; -- here we break
     b := rnd.next % 20;
     #OUT + b + "\n";
   end; 
 end;

end;</lang>

Scala

Works with: Scala version 2.7

A break library method is available in Scala 2.8 but not 2.7

<lang Scala> import scala.util.Random

val rand = new Random var doNext = true


while(doNext) { 

 val first = rand.nextInt(20)
 println(first)

 if (first != 10) {
   val second = rand.nextInt(20)
   println(second)
 } else {
   doNext = false
 }

} </lang>

Scheme

<lang scheme>(define (loop) 

 (let ((first (random 20)))
   (if (= first 10)
       (print first)
       (begin (print first)
              (print (random 20))
              (loop)))))

(loop)</lang>

SNOBOL4

Most Snobols lack a built-in rand( ) function. Kludgy "Linux-only" implementation: <lang snobol> input(.random,io_findunit(),1,"/dev/urandom") while &ALPHABET random @rand output = rand = rand - (rand / 20) * 20 eq(rand,10) :f(while) end</lang>

Or using a library function:

<lang SNOBOL4>* rand(n) -> real x | 0 <= x < n -include 'random.sno'

loop ne(output = convert(rand(20)'integer'),10) :s(loop) end</lang>

Suneido

<lang Suneido>forever 

   {
   Print(i = Random(20))
   if i is 10
       break
   Print(i = Random(20))
   }

</lang>

TI-89 BASIC

<lang ti89b>Local x Loop 

 rand(20)-1 → x
 Disp x                     © new line and text
 If x = 10 Then
   Exit
 EndIf
 Output 64, 50, rand(20)-1  © paint text to the right on same line

EndLoop</lang>

Tcl

<lang tcl>while true { 

   set a [expr int(20*rand())]
   puts $a
   if {$a == 10} {
       break
   }
   set b [expr int(20*rand())]
   puts $b

}</lang>

VBScript

Implementation

Based on BASIC version. Demonstrates breaking out of do/loop and for/next (Exit is good for getting out of functions and subs as well)

<lang vb> do a = int( rnd * 20) wscript.stdout.write a if a = 10 then exit do b = int( rnd * 20 ) wscript.echo vbnullstring,b loop

dim i for i = 1 to 100000 a = int( rnd * 20) wscript.stdout.write a if a = 10 then exit for b = int( rnd * 20 ) wscript.echo vbnullstring,b next </lang>

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