Sub..end sub

The sub..end sub control statement defines a subroutine which can be called upon from a call statement.

Syntax:  

Sub name [ ( paramlist )] statements end sub

 

Arguments are copied into the subroutine and, if the corresponding actual parameter in the call statement is a variable name, copied back out again upon exiting the subroutine.

If a subroutine has more formal parameters than actual parameters passed by a call statement, the extra parameters will be initialized to NULL and can be used as local variables within the subroutine.

Since the sub statement is a control statement and as such is ended with either a semicolon or end-of-line, each of its two clauses (sub and end sub) must not cross a line boundary.

Arguments:  

Example 1:  

Sub INCR (I,J)

I = I + 1

Exit Sub when I < 10

J = J + 1

End Sub

Call INCR (X,Y)

Example 2: - parameter transfer

Sub ParTrans (A,B,C)

A=A+1

B=B+1

C=C+1

End Sub

A=1

X=1

C=1

Call ParTrans (A, (X+1)*2)

The result of the above will be that locally, inside the subroutine, A will be initialized to 1, B will be initialized to 4 and C will be initialized to NULL.

When exiting the subroutine, the global variable A will get 2 as value (copied back from subroutine). The second actual parameter “(X+1)*2” will not be copied back since it is not a variable. Finally, the global variable C will not be affected by the subroutine call.