EXIT (function): Difference between revisions
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Note: If you have a file named t3mpdata.tmp change the file name!
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''Example 1:'' Using an ON TIMER check to read the _EXIT request return values. | ''Example 1:'' Using an ON TIMER check to read the _EXIT request return values. | ||
{{CodeStart}} | {{CodeStart}} | ||
q = {{Cl|_EXIT (function)|_EXIT}} 'function read prevents any program exit at start of program | q = {{Cl|_EXIT (function)|_EXIT}} {{Text|<nowiki>'function read prevents any program exit at start of program</nowiki>|#919191}} | ||
{{Cl|ON TIMER (n)|ON TIMER}}(5) {{Cl|GOSUB}} quit | {{Cl|ON TIMER(n)|ON TIMER}}({{Text|5|#F580B1}}) {{Cl|GOSUB}} quit | ||
{{Cl|TIMER}} ON | {{Cl|TIMER}} {{Cl|ON}} | ||
{{Cl|PRINT}} " The Timer will check for exit request every 5 seconds." | {{Cl|PRINT}} {{Text|<nowiki>" The Timer will check for exit request every 5 seconds."</nowiki>|#FFB100}} | ||
{{Cl|PRINT}} "Click the X box and/or Ctrl - Break to see the | {{Cl|PRINT}} {{Text|<nowiki>"Click the X box and/or Ctrl - Break to see the _EXIT return!"</nowiki>|#FFB100}} | ||
{{Cl|PRINT}} " Any Key Quits" | {{Cl|PRINT}} {{Text|<nowiki>" Any Key Quits"</nowiki>|#FFB100}} | ||
{{Cl|PRINT}} | {{Cl|PRINT}} | ||
{{Cl|DO}}: {{Cl|_LIMIT}} 30 | {{Cl|DO}}: {{Cl|_LIMIT}} {{Text|30|#F580B1}} | ||
{{Text|<nowiki>' ' simulated program loop</nowiki>|#919191}} | |||
{{Cl|LOOP | {{Cl|DO...LOOP|LOOP UNTIL}} {{Cl|INKEY$}} <> {{Text|<nowiki>""</nowiki>|#FFB100}} | ||
{{Cl|END}} | {{Cl|END}} | ||
| Line 39: | Line 39: | ||
{{Cl|IF}} q {{Cl|THEN}} {{Cl|PRINT}} q; | {{Cl|IF}} q {{Cl|THEN}} {{Cl|PRINT}} q; | ||
{{Cl|SELECT CASE}} q | {{Cl|SELECT CASE}} q | ||
{{Cl|CASE}} {{Text|1|#F580B1}}: {{Cl|PRINT}} {{Text|<nowiki>"= X button was clicked"</nowiki>|#FFB100}} | |||
{{Cl|CASE}} {{Text|2|#F580B1}}: {{Cl|PRINT}} {{Text|<nowiki>"= Ctrl + Break keypress"</nowiki>|#FFB100}} | |||
{{Cl|CASE}} {{Text|3|#F580B1}}: {{Cl|PRINT}} {{Text|<nowiki>"= Both X and Ctrl + Break!"</nowiki>|#FFB100}} | |||
{{Cl|END SELECT}} | {{Cl|END SELECT}} | ||
{{Cl|RETURN}} | {{Cl|RETURN}} | ||
{{CodeEnd}} | {{CodeEnd}} | ||
---- | |||
''Example 2:'' Removing temporary files before closing a program upon a user's exit request. | ''Example 2:'' Removing temporary files before closing a program upon a user's exit request. | ||
{{CodeStart}} | {{CodeStart}} | ||
x = {{Cl|_EXIT}} | x = {{Cl|_EXIT (function)|_EXIT}} {{Text|<nowiki>'initial function call blocks a user exit</nowiki>|#919191}} | ||
OPEN "t3mpdata.tmp" FOR APPEND AS #1 | {{Cl|OPEN}} {{Text|<nowiki>"t3mpdata.tmp"</nowiki>|#FFB100}} {{Cl|OPEN#File_Access_Modes|FOR}} {{Cl|OPEN#File_Access_Modes|APPEND}} {{Cl|OPEN|AS}} #1 | ||
DO | {{Cl|DO}} | ||
IF {{Cl|_EXIT}} THEN {{Cl|CLOSE}}: {{Cl|KILL}} "t3mpdata.tmp": {{Cl|_DELAY}} 1: {{Cl|SYSTEM}} | {{Cl|IF}} {{Cl|_EXIT (function)|_EXIT}} {{Cl|THEN}} {{Cl|CLOSE}}: {{Cl|KILL}} {{Text|<nowiki>"t3mpdata.tmp"</nowiki>|#FFB100}}: {{Cl|_DELAY}} {{Text|1|#F580B1}}: {{Cl|SYSTEM}} | ||
LOOP | {{Cl|LOOP}} | ||
{{CodeEnd}} | {{CodeEnd}} | ||
<center>{{Text|Note: If you have a file named ''t3mpdata.tmp'' change the file name!|red}}</center> | <center>{{Text|Note: If you have a file named ''t3mpdata.tmp'' change the file name!|red}}</center> | ||
| Line 59: | Line 60: | ||
{{PageSeeAlso}} | {{PageSeeAlso}} | ||
* [https://qb64phoenix.com/forum/showthread.php?tid=1257 Featured in our "Keyword of the Day" series] | |||
* [[SYSTEM]] | * [[SYSTEM]] | ||
* [[END]] | * [[END]] | ||
Latest revision as of 18:07, 25 May 2024
The _EXIT function prevents the user from closing a program and indicates if a user has clicked the close button in the window title (X button) or used CTRL + BREAK.
Syntax
- exitSignal% = _EXIT
Description
- Once the _EXIT function is used, the user can no longer manually exit the program until it is ended with END or SYSTEM.
- _EXIT returns any exit requests made after the initial call as:
- 0 = no exit request has been made since _EXIT monitoring began in the program.
- 1 = exit attempted by clicking the window X (close) button since last function call. (Bit 0 set)
- 2 = exit attempted with CTRL + BREAK since last call. (Bit 1 set)
- 3 = both CTRL + BREAK and the X box have been used since last call. (Bit 0 and 1 set)
- If a return value is not 0 the program can handle an exit request at a more convenient time if necessary.
- After being read, the _EXIT value is reset to 0 so store the value when a program delays an exit request.
- Note: Once _EXIT has been used once, you must monitor your program by checking it for user _EXIT requests.
- Don't just use _EXIT once to prevent a user from exiting a program early, as that constitutes bad practice.
Examples
Example 1: Using an ON TIMER check to read the _EXIT request return values.
q = _EXIT 'function read prevents any program exit at start of program ON TIMER(5) GOSUB quit TIMER ON PRINT " The Timer will check for exit request every 5 seconds." PRINT "Click the X box and/or Ctrl - Break to see the _EXIT return!" PRINT " Any Key Quits" PRINT DO: _LIMIT 30 ' ' simulated program loop LOOP UNTIL INKEY$ <> "" END quit: q = _EXIT IF q THEN PRINT q; SELECT CASE q CASE 1: PRINT "= X button was clicked" CASE 2: PRINT "= Ctrl + Break keypress" CASE 3: PRINT "= Both X and Ctrl + Break!" END SELECT RETURN |
Example 2: Removing temporary files before closing a program upon a user's exit request.
x = _EXIT 'initial function call blocks a user exit OPEN "t3mpdata.tmp" FOR APPEND AS #1 DO IF _EXIT THEN CLOSE: KILL "t3mpdata.tmp": _DELAY 1: SYSTEM LOOP |
See also