Any topic

Liberty BASIC Help Online

GOSUB label

Description:

GOSUB causes execution to proceed to the program code following the label using the form 'GOSUB label'. The label can be either a traditional line number or a branch label name enclosed in square brackets, like this: [branchLabel]. Spaces and numbers are not allowed as part of branch label names..

Here are some valid branch labels: [mainMenu] [enterLimits] [repeatHere]

Here are some invalid branch labels: [enter limits] mainMenu [1moreTime]

After execution is transferred to the point of the branch label, then each statement will be executed in normal fashion until a RETURN is encountered. When this happens, execution is transferred back to the statement immediately after the GOSUB. The section of code between a GOSUB and its RETURN is known as a 'subroutine.' One purpose of a subroutine is to save memory by having only one copy of code that is used many times throughout a program.

Usage:

print "Do you want to continue?"

gosub [yesOrNo]

if answer$ = "N" then [quit]

print "Would you like to repeat the last sequence?"

gosub [yesOrNo]

if answer$ = "Y" then [repeat]

goto [generateNew]

[yesOrNo]

input answer$

answer$ = left$(answer$, 1)

if answer$ = "y" then answer$ = "Y"

if answer$ = "n" then answer$ = "N"

if answer$ = "Y" or answer$ = "N" then return

print "Please answer Y or N."

goto [yesOrNo]

Using GOSUB [yesOrNo] in this case saves many lines of code in this example. The subroutine [yesOrNo] could easily be used many other times in such a hypothetical program, saving memory and reducing typing time and effort. This reduces errors and increases productivity.

Note: see also GOTO