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}}
: [[ON KEY(n)]] [[GOSUB]] {{Parameter|linelabel}}|{{Parameter|linenumber}}
: [[ON KEY(n)]] [[SUB]]procedure


{{PageDescription}}
* Predefined and user defined KEY event number assignments to use with ON KEY(n): 
{{WhiteStart}}     '''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$]](keyflag) + [[CHR$]]([[Keyboard scancodes|scancode]])
     '''30 and 31'''...........Reserved '''F11 and F12''' function keys only.
{{WhiteEnd}}
* See the [[KEY n]] page for user defined key or key combination presses and F function softkey assignments.
* [[GOSUB]] with a {{Parameter|linelabel}} or {{Parameter|linenumber}}  or a [[SUB]] procedure (without the [[CALL]] keyword) can be triggered in '''QB64'''.


{{PageExamples}}
''Example 1:'' Using ON KEY with [[GOSUB]] to execute code.
{{CodeStart}} '' ''
{{Cl|KEY(n)|KEY(1) ON}}
{{Cl|ON KEY(n)|ON KEY}}(1) {{Cl|GOSUB}} trap
{{Cl|PRINT}} "Press F1 to quit!"
{{Cl|DO}}:{{Cl|LOOP}}          'never ending loop

trap:
{{Cl|PRINT}} "You pressed F1 like I told you to :)"
{{Cl|END}}
{{Cl|RETURN}} '' ''
{{CodeEnd}}


''Example 2:'' Setting multiple ON KEY statements to send different values to a [[SUB]] procedure.
{{CodeStart}} '' ''
  
{{Cl|FOR...NEXT|FOR}} n = 1 {{Cl|TO}} 10
  {{Cl|KEY n|KEY}} n, {{Cl|STR$}}(n)  '   assigns soft key as a numerical string 
  {{Cl|ON KEY(n)|ON KEY}}(n) Funct n  'designate SUB procedure and parameter value passed
  {{Cl|KEY(n)|KEY}}(n) ON '         turns each key event monitor on
{{Cl|NEXT}}
{{Cl|KEY n|KEY}} ON  'displays F1 to F10 soft key assignments at bottom of screen

{{Cl|DO}}
{{Cl|LOOP}} {{Cl|UNTIL}} {{Cl|INKEY$}} = {{Cl|CHR$}}(27)
{{Cl|END}}

{{Cl|SUB}} Funct (num%)
{{Cl|CLS}}'                  clears the screen and refreshes bottom soft key list
{{Cl|PRINT}} "You pressed F"; {{Cl|LTRIM$}}({{Cl|STR$}}(num%))
{{Cl|END SUB}} '' ''
{{CodeEnd}}


{{PageSeeAlso}}
* [[KEY(n)]], [[KEY n]] {{text|(soft key)}}
* [[ON...GOSUB]], [[Scancodes]]
* [[_KEYHIT]], [[_KEYDOWN]]


{{PageNavigation}}