GWBASIC User's Manual

GW-BASIC User's Guide
GOSUB ... RETURN Statement
Purpose:
To branch to, and return from, a subroutine.
Syntax:
GOSUB line number
.
.
.
RETURN [line number]
Comments:
line number is the first line number of the subroutine.
A subroutine may be called any number of times in a program, and a subroutine may be called
from within another subroutine. Such nesting of subroutines is limited only by available memory.
A RETURN statement in a subroutine causes GW-BASIC to return to the statement following the
most recent GOSUB statement. A subroutine can contain more than one RETURN statement, should
logic dictate a RETURN at different points in the subroutine.
Subroutines can appear anywhere in the program, but must be readily distinguishable from the
main program.
To prevent inadvertent entry, precede the subroutine by a STOP, END, or GOTO statement to direct
program control around the subroutine.
Examples:
10 GOSUB 40
20 PRINT "BACK FROM SUBROUTINE"
30 END
40 PRINT "SUBROUTINE";
50 PRINT " IN";
60 PRINT " PROGRESS"
70 RETURN
RUN
SUBROUTINE IN PROGRESS
BACK FROM SUBROUTINE
The END statement in line 30 prevents re-execution of the subroutine.
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