Difference between revisions of "ON KEY(n)"

Revision as of 22:35, 26 October 2011

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

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

Description:

Predefined key numbers are shown below, where n is the number that represents that key.

1 - 10 for F1 - F10 function keys respectively

11, 12, 13 and 14 for UP, LEFT, RIGHT and DOWN numberpad arrows respectively.

15-25(29 in QB64) for user-defined keys. See: KEY n, Keyboard scancodes

30 - 31 for F11 - F12 function keys

GOSUB with a linelabel or linenumber or a SUB procedure can be used in QB64. Don't use CALL!

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 ON KEY(n) Funct n KEY(n) ON NEXT DO LOOP UNTIL INKEY$ = CHR$(27) END SUB Funct (num%) PRINT "You pressed F"; LTRIM$(STR$(num%)) END SUB

See also:

Navigation:

@@ Line 29: / Line 29: @@
-''Example 2:'' Using ON KEY with a [[SUB]] procedure to do something.
+''Example 2:'' Setting multiple ON KEY statements to send different values to a [[SUB]] procedure.
 {{CodeStart}} '' ''
-{{Cl|CLS}}
+{{Cl|FOR...NEXT|FOR}} n = 1 {{Cl|TO}} 10
+  {{Cl|ON KEY(n)|ON KEY}}(n) Funct n
+  {{Cl|KEY(n)|KEY}}(n) ON
+{{Cl|NEXT}}
-{{Cl|ON KEY(n)|ON KEY}}(10) Control 'action of user defined key press
+DO
-{{Cl|KEY(n)|KEY}}(10) ON 'turn ON event trapping for key combination
-{{Cl|PRINT}} "Press F10 key, escape quits!"
-DO: {{Cl|SLEEP}}
-  count = count + 1
-  {{Cl|PRINT}} count;
-  {{Cl|IF...THEN|IF}} {{Cl|INKEY$}} = {{Cl|CHR$}}(27) {{Cl|THEN}} {{Cl|END}} 'escape key exit
-{{Cl|LOOP}}
-{{Cl|SUB}} Control
+{{Cl|LOOP}} {{Cl|UNTIL}} {{Cl|INKEY$}} = {{Cl|CHR$}}(27)
-{{Cl|PRINT}} "F10 key pressed!";
+{{Cl|END}}
-{{Cl|BEEP}}
+{{Cl|SUB}} Funct (num%)
+{{Cl|PRINT}} "You pressed F"; {{Cl|LTRIM$}}({{Cl|STR$}}(num%))
 {{Cl|END SUB}} '' ''
 {{CodeEnd}}