View source for Befunge

A 2d programming language named after a spelling of "before".

=Instructions=
{| class="wikitable"
!Cmd
!Description
|-
|<code>+</code>
|Addition: Pop two values a and b, then push the result of a+b
|-
|<code>-</code>
|Subtraction: Pop two values a and b, then push the result of b-a
|-
|<code>*</code>
|Multiplication: Pop two values a and b, then push the result of a*b
|-
|<code>/</code>
|Integer division: Pop two values a and b, then push the result of b/a, rounded down. According to the specifications, if a is zero, ask the user what result they want.
|-
|<code>%</code>
|Modulo: Pop two values a and b, then push the remainder of the integer division of b/a.
|-
|<code>!</code>
|Logical NOT: Pop a value. If the value is zero, push 1; otherwise, push zero.
|-
|<code>`</code>
|Greater than: Pop two values a and b, then push 1 if b>a, otherwise zero.
|-
|<code>&gt;</code>
|PC direction right
|-
|<code>&lt;</code>
|PC direction left
|-
|<code>^</code>
|PC direction up
|-
|<code>v</code>
|PC direction down
|-
|<code>?</code>
|Random PC direction
|-
|<code>_</code>
|Horizontal IF: pop a value; set direction to right if value=0, set to left otherwise
|-
|<code><nowiki>|</nowiki></code>
|Vertical IF: pop a value; set direction to down if value=0, set to up otherwise
|-
|<code>"</code>
|Toggle stringmode (push each character's ASCII value all the way up to the next <code>"</code>)
|-
|<code>:</code>
|Duplicate top stack value
|-
|<code>\</code>
|Swap top stack values
|-
|<code>$</code>
|Pop top of stack and discard
|-
|<code>.</code>
|Pop top of stack and output as integer
|-
|<code>,</code>
|Pop top of stack and output as ASCII character
|-
|<code>#</code>
|Bridge: jump over next command in the current direction of the current PC
|-
|<code>g</code>
|A "get" call (a way to retrieve data in storage). Pop two values y and x, then push the ASCII value of the character at that position in the program. If (x,y) is out of bounds, push 0
|-
|<code>p</code>
|A "put" call (a way to store a value for later use). Pop three values y, x and v, then change the character at the position (x,y) in the program to the character with ASCII value v
|-
|<code>&</code>
|Get integer from user and push it
|-
|<code>~</code>
|Get character from user and push it
|-
|<code>@</code>
|End program
|-
|<code>0</code> – <code>9</code>
|Push corresponding number onto the stack
|}

=Examples=
 >              v
  v"Hello World!"<
  >:v
  ^,_@

 ~:1+!#@_,

 &#::_.@#

I won't explain what those do :)