sub ... end sub
Subroutine definition.
Syntax:
sub name ( parmlist {...} )
block of instructions
end sub
name is the subroutine name, it's an alphanumeric string who must starts with a non numeric character. For example: 1printString is incorrect while printString1 is correct.
parmlist are one or more variables used to pass argument to the subroutine.
While writing programs may happen you need to repeat the same sequence of instructions in several parts of the program. sdlBasic offer you the chance of write the instruction sequence one time and then recall it from every part of the program may needs it. Variables used inside the subroutine are local variables, that means they will not influence other variables that happens to use the same variable name in your main program or in any other subroutine. This is valid for arrays too. See Commons, Shared and Dim statements.
You can pass a list of parameters to your subroutine, but, unlike Function, you can't return any results. Subroutine that do not require input parameters can be used in your main program without brackets.
Example:
Sub printString(a$)
prints(a$)
end Sub
printString("yo!!!")
See also Commons, Shared and Dim commands.