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--- el:subroutine [2016/01/01 22:40]
+++ el:subroutine [2020/02/28 10:46] (current)
@@ Line 1: / Line 1: @@
+===== Subroutine =====
+==== Format ====
+**subroutine** subroutinename ( //variable list// )\\
+//statements//\\
+**end subroutine**
+**subroutine** subroutinename$ ( //variable list// )\\
+//statements//\\
+**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, numeric or string variables.  Arrays and variables may be passed by reference using the [[Ref|Ref]] definition.
+Subroutines should be defined at the bottom of your program, and 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 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}}
+==== New To Version ====
+.9.9.1

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