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69 lines
1.9 KiB
Markdown
69 lines
1.9 KiB
Markdown
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The [ON KEY(n)](ON-KEY(n)) statement defines a line number or label to go to (or a [SUB](SUB) to run) when a specified key is pressed.
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## Syntax
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> [ON KEY(n)](ON-KEY(n)) [GOSUB](GOSUB) linelabel|linenumber
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> [ON KEY(n)](ON-KEY(n)) [SUB](SUB)procedure
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## Description
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* Predefined and user defined KEY event number assignments to use with ON KEY(n):
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```text
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**1 to 10**.............Reserved **F1 to F10** function keys only.
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**11, 12, 13 and 14**...Reserved **Up, Left, Right and Down** numeric keypad arrows only
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**15 to 29**............**user-defined keys** using value: [CHR$](CHR$)(keyflag) + [CHR$](CHR$)([Keyboard scancodes](Keyboard-scancodes))
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**30 and 31**...........Reserved **F11 and F12** function keys only.
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```
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* See the [KEY n](KEY-n) page for user defined key or key combination presses and F function softkey assignments.
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* [GOSUB](GOSUB) with a linelabel or linenumber or a [SUB](SUB) procedure (without the [CALL](CALL) keyword) can be triggered in **QB64**.
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## Example(s)
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Using ON KEY with [GOSUB](GOSUB) to execute code.
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```vb
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KEY(1) ON
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ON KEY(1) GOSUB trap
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PRINT "Press F1 to quit!"
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DO:LOOP 'never ending loop
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trap:
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PRINT "You pressed F1 like I told you to :)"
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END
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RETURN
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```
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Setting multiple ON KEY statements to send different values to a [SUB](SUB) procedure.
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```vb
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FOR n = 1 TO 10
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KEY n, STR$(n) ' assigns soft key as a numerical string
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ON KEY(n) Funct n 'designate SUB procedure and parameter value passed
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KEY(n) ON ' turns each key event monitor on
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NEXT
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KEY ON 'displays F1 to F10 soft key assignments at bottom of screen
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DO
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LOOP UNTIL INKEY$ = CHR$(27)
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END
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SUB Funct (num%)
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CLS' clears the screen and refreshes bottom soft key list
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PRINT "You pressed F"; LTRIM$(STR$(num%))
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END SUB
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```
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## See Also
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* [KEY(n)](KEY(n)), [KEY n](KEY-n) (soft key)
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* [ON...GOSUB](ON...GOSUB), [Scancodes](Scancodes)
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* [_KEYHIT](_KEYHIT), [_KEYDOWN](_KEYDOWN)
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