'''KEY(n)''' assigns, enables, disables or suspends event trapping of a keypress by setting the flag [[ON]], [[STOP]] or [[OFF]].


{{PageSyntax}}
: KEY({{Parameter|number}}) {[[ON]] | [[OFF]] | [[STOP]]}


{{PageDescription}}
* Predefined and user defined KEY event number assignments to use with 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}}
* Keypresses can be read during [[INKEY$]], [[INPUT$]] or [[INPUT]] procedures without losing the input. 
* Key event reads will also interrupt [[SLEEP]]. 
* [[KEY(n)]] specific status modes are:
**'''ON''' enables specific keypress events to be monitored. 
**'''STOP''' suspends specific keypress reads, but remembers them. When re-enabled the key presses will be returned.
**'''OFF''' disables specified keypress reads and will not remember the event.


{{PageExamples}}
''Example 1:'' How to trap the LEFT direction keys on both the dedicated cursor keypad and the numeric keypad.
{{CodeStart}} '' ''
{{Cl|KEY n|KEY}} 15, {{Cl|CHR$}}(128) + {{Cl|CHR$}}(75) ' Assign trap for LEFT arrow key on the cursor keypad
{{Cl|ON KEY(n)|ON KEY(15)}} {{Cl|GOSUB}} CursorPad     
{{Cl|KEY(n)|KEY(15)}} {{Cl|ON}} ' enable event trapping                   

{{Cl|ON KEY(n)|ON KEY(12)}} {{Cl|GOSUB}} NumericPad ' Trap LEFT key on number pad
{{Cl|KEY(n)|KEY(12)}} {{Cl|ON}} ' enable event trapping                      

DO
LOOP UNTIL UCASE$(INKEY$) = "Q" ' Idle loop for demo
{{Cl|SYSTEM}}

CursorPad:
PRINT "Pressed LEFT key on cursor keypad."
{{Cl|RETURN}}

NumericPad:
PRINT "Pressed LEFT key on numeric keypad."
RETURN '' ''
{{CodeEnd}}


''Example 2:'' Trapping the F5 keypress.
{{CodeStart}} '' ''
{{Cl|KEY(n)|KEY(5)}} {{Cl|ON}}
{{Cl|ON KEY(n)|ON KEY(5)}} {{Cl|GOSUB}} execute
{{Cl|PRINT}} "Press F5 (or ESC) to quit!)"
{{Cl|DO}}
{{Cl|LOOP}} {{Cl|UNTIL}} {{Cl|INKEY$}} = {{Cl|CHR$}}(27) ' idle loop
{{Cl|SYSTEM}}
execute:
PRINT "You pressed the F5 key..."
{{Cl|SLEEP}} 1
PRINT "Press any key to continue..."
SLEEP '' ''
{{CodeEnd}}


{{PageSeeAlso}}
* [[ON KEY(n)]], [[KEY n]] {{text|(softkeys)}}
* [[_KEYHIT]], [[_KEYDOWN]]
* [[Keyboard scancodes]]


{{PageNavigation}}