|Liberty BASIC Help Online
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.
print "Do you want to continue?"
if answer$ = "N" then [quit]
print "Would you like to repeat the last sequence?"
if answer$ = "Y" then [repeat]
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."
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.
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