===== Subroutine (Statement) =====

==== Format ====
**subroutine** subroutine_name ( [[functionvariablelist|function_variable_list]] )\\
(tab)[[programsyntax|statement(s)]]\\
**end subroutine**

==== Description ====
Create a subroutine (or subprogram) that will receive zero or more values and process those values.  A subroutine does not return a value back to the user, it just does what you want it to do.  Execution of a subroutine will terminate and control will be returned to the "[[call|call]]ing" program when a [[Return|Return]] statement is executed or by allowing the //End Subroutine// statement to be reached.  All variables used within the subroutine, that have not been previously declared as [[global|Global]], will be local to the subroutine and will not change the values in the calling code.

Subroutine variables may a list of zero or more, comma separated, variables.  Arrays and variables may be passed by reference using the [[Ref|Ref]] definition.

Subroutines should be defined anywhere on your program, but can not be defined within another [[function|Function]], [[Subroutine|Subroutine]] or control block ([[ifthen|If/Then]], [[dountil|Do/Until]], ...)

==== Example ====

<code>
# 100 random circles
clg
for x = 1 to 100
   call draw()
next x
end

function rnd(n)
   rnd = int(rand*n)
end function

subroutine draw()
   color rgb(rnd(256),rnd(256),rnd(256))
   circle rnd(graphwidth), rnd(graphheight), rnd(graphwidth/10)
end subroutine
</code>
draws\\
{{:en:subroutine_circle.png|Circles}}
==== See Also ====
{{page>en:start#Program Control&noheader}}

==== History ==== 
|0.9.9.1|New To Version|