qb45advr.hlp (
Topic list)
Important Notice
The pages on this site contain documentation for very old MS-DOS software,
purely for historical purposes.
If you're looking for up-to-date documentation, particularly for programming,
you should not rely on the information found here, as it will be woefully
out of date.
ON KEY(n) Statement Details
◄QuickSCREEN► ◄Details► ◄Example► ◄Contents► ◄Index►
──────────────────────────────────────────────────────────────────────────────
ON KEY(n) Statement Details
Syntax
ON KEY(n) GOSUB {linelabel | linenumber}
Keys are processed in the following order:
1. The line printer's echo-toggle key is processed first. Defining
this key as a user-defined key trap does not prevent characters
from being echoed to the line printer when pressed.
2. Function keys and the cursor-direction keys are examined next.
Defining a FUNCTION key or DIRECTION key as a user-defined key
trap has no effect because these keys are predefined.
The ON KEY statement can trap any key, including BREAK or system reset.
This makes it possible to prevent accidentally breaking out of a program
or rebooting the machine.
Note: When a key is trapped, the key event is destroyed. You cannot
subsequently use INPUT or INKEY$ statements to find out which
key caused the trap. Because there is no way to know which key
press caused the branch to the trap, you must set up a subroutine
for each key if you want to assign different functions to
particular keys.