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Purpose |
Send program flow to one of several possible destinations based on the value of a numeric expression. |
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Syntax |
ON n GOTO {label | line_number} [, {label | line_number}] ... |
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Remarks |
n is a numeric expression ranging from 1 to 255, and label or line_number identifies a statement in the program to branch to. The nth label is branched to; for example, if n equals 4, the fourth label in the list receives control. If n is less than one or greater than the number of labels in the list, program execution continues with the statement that immediately follows the ON GOTO statement. ON GOTO behaves exactly like ON GOSUB, except that it performs a GOTO rather than a GOSUB. This means that the program retains no memory of where the branch originated. ON GOTO can only branch to labels or line numbers that have the same scope as the ON GOTO statement. The SELECT and IF blocks also perform multiple branching, and are more flexible than ON GOTO. See the GOTO entry for a discussion of ways to avoid using GOTOs in your programs. Note that ON GOTO (and ON GOSUB) have been internally optimized to produce greater run-time performance than was possible with previous versions of PowerBASIC. |
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See also |
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Example |
SUB Main FOR I& = 1 TO 3 ON I& GOTO OneHandler, TwoHandler, ThreeHandler Back: NEXT I& EXIT SUB
OneHandler: Message$ = "Handler number" + STR$(I&) GOTO Back
TwoHandler: Message$ = "Handler number" + STR$(I&) GOTO Back
ThreeHandler: Message$ = "Handler number" + STR$(I&) GOTO Back END SUB |
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Result |
Handler number 1 Handler number 2 Handler number 3 |