ON...GOSUB: Difference between revisions
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(Created page with "ON...GOSUB is a control-flow statement that branches to a line or label in a list depending on a numerical expression. {{PageSyntax}} : '''ON''' {{Parameter|numericalExpression}} GOSUB {{Parameter|labelOrNumber}}[,{{Parameter|labelOrNumber}}][,...] {{PageDescription}} * {{Parameter|numericalExpression}} represents the ''line'' or ''label'' that the program should branch to: 1 branches to the first line or label in the list, 2 branches to the second, etc. * Th...") |
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* '''Note:''' [[SELECT CASE]] provides a much more convenient way of doing this task. | * '''Note:''' [[SELECT CASE]] provides a much more convenient way of doing this task. | ||
=== QBasic/QuickBASIC === | |||
==QBasic/QuickBASIC== | |||
* In QuickBASIC 4.5 the list could contain a maximum of 60 line numbers or labels, while '''QB64''' has no limit. | * In QuickBASIC 4.5 the list could contain a maximum of 60 line numbers or labels, while '''QB64''' has no limit. | ||
| Line 19: | Line 18: | ||
{{PageExamples}} | {{PageExamples}} | ||
''Example:'' | ''Example:'' | ||
{{CodeStart}} | {{CodeStart}} | ||
{{Cl|CLS}} | {{Cl|CLS}} | ||
a = 2 | a = 2 | ||
{{Cl|ON...GOSUB|ON}} a {{Cl|ON...GOSUB|GOSUB}} hello, hereweare, 143 | |||
{{Cl|PRINT}} "Also notice the RETURN statement that can be used with GOSUB!" | {{Cl|PRINT}} "Also notice the RETURN statement that can be used with GOSUB!" | ||
{{Cl|END}} | {{Cl|END}} | ||
| Line 36: | Line 35: | ||
143 | 143 | ||
{{Cl|PRINT}} "Line 143, with a = 3 you get to see this!" | {{Cl|PRINT}} "Line 143, with a = 3 you get to see this!" | ||
{{Cl|END}} | {{Cl|END}} | ||
{{CodeEnd}} | {{CodeEnd}} | ||
{{OutputStart}} | {{OutputStart}} | ||
| Line 48: | Line 47: | ||
{{PageSeeAlso}} | {{PageSeeAlso}} | ||
* [[ON...GOTO]] | * [[ON...GOTO]] | ||
* [[GOSUB]], [[GOTO]] | * [[GOSUB]], [[GOTO]] | ||
* [[SELECT CASE]], [[RETURN]] | * [[SELECT CASE]], [[RETURN]] | ||
{{PageNavigation}} | {{PageNavigation}} | ||
Latest revision as of 22:05, 21 February 2023
ON...GOSUB is a control-flow statement that branches to a line or label in a list depending on a numerical expression.
Syntax
- ON numericalExpression GOSUB labelOrNumber[,labelOrNumber][,...]
Description
- numericalExpression represents the line or label that the program should branch to: 1 branches to the first line or label in the list, 2 branches to the second, etc.
- The procedure must be used after the number value is determined or in a loop to monitor current user events.
- RETURN returns to the next code statement after the ON...GOSUB statement. END or SYSTEM can be used to end program.
- Note: SELECT CASE provides a much more convenient way of doing this task.
QBasic/QuickBASIC
- In QuickBASIC 4.5 the list could contain a maximum of 60 line numbers or labels, while QB64 has no limit.
Examples
Example:
CLS a = 2 ON a GOSUB hello, hereweare, 143 PRINT "Also notice the RETURN statement that can be used with GOSUB!" END hello: PRINT "Hello, with a = 1 you get to see this!" END hereweare: PRINT "with a = 2 here we are...return to line after ON." RETURN 143 PRINT "Line 143, with a = 3 you get to see this!" END |
with a = 2 here we are...return to line after ON. Also notice the RETURN statement that can be used with GOSUB! |
- Explanation: Since a equals to 2 it goes to the second item in the list (hereweare) and branches the program to there. Try changing 'a' to 1 or 3.
See also