10 PRINT CHR$(205.5+RND(1)); : GOTO 10 in PHP (or anything else, for that matter)

Question

Just had a 'spirited' conversation with a co-worker about the succinctness of the following BASIC statement:

10 PRINT CHR$(205.5+RND(1)); : GOTO 10

It's the title of this book, and will simply print a sequence of / and \ characters, alternating between the two randomly, resulting in a pattern similar to this:

(Image borrowed from http://www.flickr.com/photos/rndmcnlly/5058442151/sizes/o/in/photostream/)

Being of a PHP proclivity, we wondered what the most compact way of writing the same thing in PHP would be, and came up with this:

while(1) { echo chr(47 + 45 * rand(0,1)); }

chr(47) is a / character, and chr(92) is a \. So the statement echo chr(47 + 45 * rand(0,1)); will randomly alternate between the two, ad nauseam.

In a language of your choosing, write the shortest program or function to output an infinite random sequence of \ and / characters, where each character has an equal probability of being chosen.

Answer 1

Since this has been migrated to codegolf...

PHP 30 bytes

<?for(;;)echo rand(0,1)?~Ð:~£;

The Ð is character 208, and the £ is character 163.

Sample usage (on a Windows box):

color 18 & php maze.php

Produces something similar to:

It works best with a monospace font that is exactly square (here I've chosen the standard system font 8x8). To go back to your default color, you can type color again without any parameters.

Answer 2

Mathematica 157 bytes

Lacking PETSCII, I rolled my own "\" and "/".

No cigar for brevity here.

Graphics[{Thickness[.005],RGBColor[0.73,0.55,1.],Line/@Flatten[Table[RandomChoice[{{{x,y},{x+1,y+1}},{{x+1,y},{x,y+1}}}],{x,40},{y,25}],1]},Background->Blue]

Answer 3

The goto operator was added to PHP from version 5.3.0 so you could use the same method as you would in BASIC:

a: echo chr(47 + 45 * rand(0,1)); goto a;

Answer 4

Brainfuck - 534

>+[->>>>>>[<<<<<<+>>>>>>-]>[<<<<<<+>>>>>>-]<<<<+++++++[<+++++++++++>-]
<[<<[>>>>>>+<<<+<<<-]>>>[<<<+>>>-]<<[>>>>>+<<<+>+<<<-]>>>[<<<+>>>-]<[>
>>>+[<<<+>+>>-]<<[>>+<<-]+<[>-<[-]]>[>+<-]<<-]<-]++++++[>++++++++<-]>-
[<<[>>>>>+<<<<+<-]>[<+>-]>-]<<<[-]>[-]+++++[<+++++>-]<[>>>>>>>+[<<<<<<
+>+>>>>>-]<<<<<[>>>>>+<<<<<-]+<[>-<[-]]>[>>>>+<<<<-]<<-]++++++[>>>>>>+
++++++++<<<<<<-]>>>>>>[<<<<<<<+>+>>>>>>-]<<<<<<[>>>>>>+<<<<<<-]++<[->-
[>+>>]>[+[-<+>]>+>>]<<<<<]>[-]>>[-]<[<<+>+>-]<<[>>+<<-]+>>[-]<[++++[>+
+++<---]>.[-]<<->]<[[>+<+++++]>----.[-]<]>+]

My prng (from here) is both large and extremely slow. Perhaps a simpler LFSR or similar would suffice, but this works:

Answer 5

Befunge, 12 9 8 7 Bytes

Edit: James Holderness figured out an insane solution that uses three quotes instead.

?\","/"

Overflows the stack with a lot of excess characters for each symbol, but who cares when you can golf that 1 byte?

Old version

"/\"?>,#

(Note the trailing space) Trailing space apparently not needed (thanks MercyBeaucou)

Try It Online

"/\" Adds both / and \ to the stack
    ? Chooses a random direction to go in. Both up and down loop back around to the ? so it's 50% chance to go in either direction.
Going left
"/\"  >,#  Adds \ and / to the stack but only print the second, the / before heading back
Going right
      >,# Prints the top of the stack, the \ before heading back

This does start to fill up the stack, with one extra symbol for every symbol printed.

Answer 6

C, 39 chars (38 on MSVC)

main(){while(putchar(rand()%2?47:92));}

See it run.

On MSVC, we can replace putchar() with _putch() and save a byte, but it doesn't work in IDEOne.

main(){while(_putch(rand()%2?47:92));}

Answer 7

Common Lisp, 33

(loop(princ(elt"/\\"(random 2))))

Answer 8

Jelly, 5 bytes

Ø^XȮß

Try it online!

XØ^ß is a byte shorter, but prints a 0 before the slashes.

  X      Choose a random element from
Ø^       "/\",
   Ȯ     print it,
    ß    then call this link again.

Answer 9

print has a return value of 1, so if you use that you can just wrap the whole expression in the while:

while(print chr(47 + 45 * rand(0,1));

You can probably golf it further too.

Answer 10

Vyxal, 5 bytes

{k/℅₴

No trying it online

It was a smart choice adding all of the two byte constants of 05ab1e and Jelly.

Answer 11

C (gcc), 47 bytes

main(){while(putchar(47+45*(rand()/(1<<30))));}

Try it online!

Answer 12

Python 3, 59 51 bytes

Using only 1 line (in the spirit of the original 10 PRINT):

from random import*;exec("while 1:print(end=choice('\/'))")

while 1:from random import*;print(end=choice('\/'))

Or (possibly not that random) using hash for just 47 bytes (but on 2 lines):

x=0
while 1:x=hash(str(x));print(end='\/'[x%2])

Try it online!

Answer 13

ruby, 27 23 chars

loop{$><<"/\\"[rand 2]}

$><< is 'print to stdout'.

Answer 14

C++, 45 Chars

int main(){for(;;)cout<<(rand()%2?"/":"\\");}

Not going to win any awards for shortness, but I had already written this when I heard about the mentioned book, so I just golfed it.

The putchar trick also works in C++, getting you down to 43, but you can't avoid declaring the return type on main.

Answer 15

i try create using css style, and it's work

<style>
  body {
    font-family: monospace;
    line-height:75%;
    letter-spacing:-3px;
  }
</style>

this php code :

<?php
  $i=10000;
  while($i) {
    if($i%200 == 0) echo '<br/>';
    echo chr(47 + 45 * rand(0,1));
    $i--;
  }
?>

Answer 16

Common Lisp - 68

(defun s(l)(elt l(random(length l))))(loop do(format t"~a"(s"/\\")))

Answer 17

Python, 68

In the "my language sucks at this" category, we've got Python!

import random,sys
while 1:sys.stdout.write(random.choice('/\\'))

Thanks to Ivo for a few chars on imports and choice.

Answer 18

16-bit x86 assembly code, 10 bytes

I don't remember if this one ended up in the book.

init:
scasb            ;read from where ES:DI points and compare to AL 
                 ;this sets flags similar to a subtraction 
salc             ;set mask in AL to 00 or FF 
and   al,'\'-'/' ;begin choosing character (AL is 00 or 2D) 
add   al,'/'     ;finish choosing character 
writec:
int   29h        ;write char in AL 
jmp   init       ;loop endlessly

Answer 19

05AB1E, 7 bytes

["/\"Ω?

Try it online!

["/\"Ω?  - Full program
[          Start an infinite loop
 "/\"      ... Push the string "/\" on the stack
     Ω     ... Pick a character from the top of the stack, at random
      ?    ... Print without a newline

Answer 20

Befunge-98 (PyFunge), 7 bytes

? '/,\'

Try it online!

the ? sends the IP either left or right, so either / or \ is pushed before printing with ,. When executing the '/ or \' in the wrong order after printing, it just does things to the stack (divides or swaps), and then pushes an irrelevant character before repeating.

Answer 21

PHP, 26 31 bytes

eight three bytes shorter than yours (without whitespace or braces),
two bytes shorter than primo´s solution (without the tag).

PHP 5.4.9 was the current version in December 1012, so ...

for($s="\/";;)echo$s[rand()%2];

requires PHP 5.5 or later for literal string indexing.

Run with -r or try it online.

Answer 22

Keg, 12 bytes

You do not have to worry about the evenness 0f the output, because the range is 0 to 32767, and 32767+1 = 32768; it is an even number.

{~2%[\\|\/],

Answer 23

HTML+JS, 186

<pre style="letter-spacing:-3.5px;line-height:9px;;white-space: pre-wrap;line-break: anywhere;" onclick="setInterval(_=>this.innerHTML+='/\\'[2*Math.random()|0])">C l i c k   m e !</pre>

Answer 24

Not much better. Needs php 5.5+ for the array dereferencing feature.

while(1) { echo ['/', '\\'][rand(0, 1)]; }

Answer 25

><>, 14 bytes

I was hoping I could restrict it to a 3*3 square but didn't succeed.

"/\
~x/
o</
 !

You can try it here.

Answer 26

Cubix, 12 bytes

D<^<!"/\"B!o

View in the online interpreter!

This maps out to the following cube net:

    D <
    ^ <
! " / \ " B ! o
. . . . . . . .
    . .
    . .

Explanation

Setup:

The IP begins heading east at the first !. This is the 'skip if truthy' command, which is False when there is nothing on stack, so no commands are skipped. "/\" enters stringmode and appends these two character codes to the stack. B!o is mostly a no-op here, only reversing the stack.

The IP now loops back around to the first !. However, there are now positive integers on stack, so the first " is skipped. This means / is no longer a character, but a mirror, sending the IP north into the main loop.

Main Loop:

The D command is the only source of randomness in Cubix. It sends the IP in a random direction. By blocking off South and East with arrows, we make sure the IP has a 50% chance of heading North, and a 50% chance of heading West.

If it heads West, the stack is reversed. If it heads North, the top character is printed.

This creates the random sequence of slashes, as desired.

Answer 27

SmileBASIC, 20 bytes

?"/\"[RND(2)];
EXEC.

Answer 28

PowerShell, 108 90 86 54 53 37 36 bytes

for(){Write-Host "\/"[(Random 2)]-n}

Try it online!

Answer 29

Java 8, 60 59 54 53 bytes

v->{for(;;)System.out.write(Math.random()<.5?47:92);}

-1 byte thanks to @BenjaminUrquhart by replacing print with write, so '/' can be 47.

Explanation:

Try it online (times out after 60 sec).

v->{                     // Method with empty unused parameter and no return-type
  for(;;)                //  Loop indefinitely
    System.out.write(    //   Print:
      Math.random()<.5?  //    If the random decimal value in range [0,1) is below 0.5:
       47                //     Print forward slash
      :                  //    Else:
       92);}             //     Print backward slash

Answer 30

Cubix, 10 bytes

Du\'^>o$/;

Watch it run

    D u
    \ '
^ > o $ / ; . .
. . . . . . . .
    . .
    . .

Was an interesting one to do as i haven't played with the random direction generator much.

• ^D redirect to the random direction pointer

Directed north

• o\> loops around the cube, print empty stack and redirecting back into the print commands (stack is empty)

Directed west

• ^ redirected back into the random direction pointer

Directed south

• \'/> reflected to the east, push / onto the stack and redirect into the print commands

Directed east

• u'\> uturn to the right, push \ onto the stack and redirect into the print commands

Print commands

• o$/;^ output top of stack, skip over the reflect, pop from the stack and redirect into the random direction pointer