dos_compilers/Microsoft QuickBASIC v3/manual/ng16dd7.html
2024-07-01 13:00:14 -07:00

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<B>KEY(n) Enable/Disable Key Trapping</B>
<B>KEY</B>(<U>n</U>) {ON | OFF | STOP}
Enables or disables the trapping of a specified key via ON KEY(<U>n</U>).
<U>n</U> A numeric expression in the range 1 to 20, specifying the
key to trap, as follows:
1-10,30,31 Function keys F1 through F10, F11, F12
11 Cursor Up
12 Cursor Left
13 Cursor Right
14 Cursor Down
15-25 Keys defined via KEY <U>n</U>, CHR$(<U>KBflag</U>) +
CHR$(<U>scancode</U>)
ON KEY(<U>n</U>) ON activates trapping. If an ON KEY(<U>n</U>) GOSUB
statement has been executed, QuickBASIC checks before
executing each statement to see if the specified key has
been pressed. If it has, QuickBASIC performs the indicated
GOSUB.
OFF KEY(<U>n</U>) OFF deactivates trapping.
STOP KEY(<U>n</U>) STOP also deactivates trapping, but QuickBASIC
continues checking to see if the specified key has been
pressed. If it has been pressed, a subsequent KEY(<U>n</U>) ON
results in an immediate trap (provided an ON KEY(<U>n</U>)
statement with a nonzero line number has been executed).
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<B>Notes:</B> If the "Checking Between Statements" option is in effect,
QB checks for communication activity after each statement.
If the "Event Trapping" option is selected, QB checks
after each new program line. If neither option is
selected, no trapping takes place.
For command-line compilation, /v enables checking after
each statement, and /w enables checking after each new
line. If neither switch is used, no trapping takes place.
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<B>See Also:</B>
<A HREF="ng1e384.html">ON KEY</A>
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