Difference between revisions of "ON KEY(n)"

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imported>SMcNeill
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The '''ON KEY(n)''' statement defines a line number or label to go to when a specified key is pressed. QB64 can reference a [[SUB]].
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The [[ON KEY(n)]] statement defines a line number or label to go to (or a [[SUB]] to run) when a specified key is pressed.
  
  
 
{{PageSyntax}}
 
{{PageSyntax}}
:: ON KEY (n) {{{KW|GOSUB}} {''linelabel''|''linenumber''}|{{KW|SUB}}procedure}
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: [[ON KEY(n)]] [[GOSUB]] {{Parameter|linelabel}}|{{Parameter|linenumber}}
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: [[ON KEY(n)]] [[SUB]]procedure
  
  
''Description:''
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{{PageDescription}}
* Predefined key numbers are shown below, where n is the number that represents that key.
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* Predefined and user defined KEY event number assignments to use with ON KEY(n):
:'''1 - 10''' for '''F1 - F10''' function keys respectively
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{{WhiteStart}}    '''1 to 10'''.............Reserved '''F1 to F10''' function keys only.
:'''11, 12, 13 and 14''' for '''UP, LEFT, RIGHT and DOWN''' numberpad arrows respectively.
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    '''11, 12, 13 and 14'''...Reserved '''Up, Left, Right and Down''' numeric keypad arrows only
:'''15-25(29 in QB64)''' for '''user-defined keys'''. See: [[KEY n]], [[Keyboard scancodes]]
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    '''15 to 29'''............'''user-defined keys''' using value: [[CHR$]](keyflag) + [[CHR$]]([[Keyboard scancodes|scancode]])
:'''30 - 31''' for '''F11 - F12''' function keys
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    '''30 and 31'''...........Reserved '''F11 and F12''' function keys only.
* [[GOSUB]] with a ''linelabel'' or ''linenumber'' or a [[SUB]] procedure can be used in '''QB64'''. Don't use [[CALL]]!
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{{WhiteEnd}}
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* See the [[KEY n]] page for user defined key or key combination presses and F function softkey assignments.
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* [[GOSUB]] with a {{Parameter|linelabel}} or {{Parameter|linenumber}} or a [[SUB]] procedure (without the [[CALL]] keyword) can be triggered in '''QB64'''.
  
  
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{{PageExamples}}
 
''Example 1:'' Using ON KEY with [[GOSUB]] to execute code.
 
''Example 1:'' Using ON KEY with [[GOSUB]] to execute code.
 
{{CodeStart}} '' ''
 
{{CodeStart}} '' ''
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{{Cl|KEY n|KEY}} ON  'displays F1 to F10 soft key assignments at bottom of screen
 
{{Cl|KEY n|KEY}} ON  'displays F1 to F10 soft key assignments at bottom of screen
  
DO
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{{Cl|DO}}
 
 
 
{{Cl|LOOP}} {{Cl|UNTIL}} {{Cl|INKEY$}} = {{Cl|CHR$}}(27)
 
{{Cl|LOOP}} {{Cl|UNTIL}} {{Cl|INKEY$}} = {{Cl|CHR$}}(27)
 
{{Cl|END}}
 
{{Cl|END}}
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''See also:''
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{{PageSeeAlso}}
 
* [[KEY(n)]], [[KEY n]] {{text|(soft key)}}
 
* [[KEY(n)]], [[KEY n]] {{text|(soft key)}}
 
* [[ON...GOSUB]], [[Scancodes]]
 
* [[ON...GOSUB]], [[Scancodes]]

Latest revision as of 03:15, 16 October 2017

The ON KEY(n) statement defines a line number or label to go to (or a SUB to run) when a specified key is pressed.


Syntax

ON KEY(n) GOSUB linelabel|linenumber
ON KEY(n) SUBprocedure


Description

  • Predefined and user defined KEY event number assignments to use with ON KEY(n):

1 to 10.............Reserved F1 to F10 function keys only. 11, 12, 13 and 14...Reserved Up, Left, Right and Down numeric keypad arrows only 15 to 29............user-defined keys using value: CHR$(keyflag) + CHR$(scancode) 30 and 31...........Reserved F11 and F12 function keys only.

  • See the KEY n page for user defined key or key combination presses and F function softkey assignments.
  • GOSUB with a linelabel or linenumber or a SUB procedure (without the CALL keyword) can be triggered in QB64.


Examples

Example 1: Using ON KEY with GOSUB to execute code.

KEY(1) ON ON KEY(1) GOSUB trap PRINT "Press F1 to quit!" DO:LOOP 'never ending loop trap: PRINT "You pressed F1 like I told you to :)" END RETURN


Example 2: Setting multiple ON KEY statements to send different values to a SUB procedure.

FOR n = 1 TO 10 KEY n, STR$(n) ' assigns soft key as a numerical string ON KEY(n) Funct n 'designate SUB procedure and parameter value passed KEY(n) ON ' turns each key event monitor on NEXT KEY ON 'displays F1 to F10 soft key assignments at bottom of screen DO LOOP UNTIL INKEY$ = CHR$(27) END SUB Funct (num%) CLS' clears the screen and refreshes bottom soft key list PRINT "You pressed F"; LTRIM$(STR$(num%)) END SUB


See also



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