SCREENEXISTS: Difference between revisions
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(Created page with "{{DISPLAYTITLE:_SCREENEXISTS}} The _SCREENEXISTS function returns true (-1) once a screen has been created. {{PageSyntax}} : {{Parameter|screenReady%%}} = _SCREENEXISTS {{PageDescription}} * Function returns true (-1) once a program screen is available to use or change. * Can be used to avoid program errors because a screen was not ready for input or alterations. ** Use before _TITLE, _SCREENMOVE and other functions that require the output window to h...") |
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{{PageExamples}} | {{PageExamples}} | ||
;Example:Waiting in a loop until the screen exists to add the title. The [[_LIMIT]] prevents the loop from using all CPU time while waiting. | |||
{{CodeStart}} | {{CodeStart}} | ||
{{Cl|SCREEN}} 12 | {{Cl|SCREEN}} 12 | ||
{{Cl|DO}}: {{Cl|LOOP}} {{Cl|UNTIL}} | {{Cl|DO}}: {{Cl|_LIMIT}} 10: {{Cl|LOOP}} {{Cl|UNTIL}} {{Cl|_SCREENEXISTS}} | ||
{{Cl|_TITLE}} "My Title" | {{Cl|_TITLE}} "My Title" | ||
{{CodeEnd}} | {{CodeEnd}} | ||
Latest revision as of 17:29, 25 November 2022
The _SCREENEXISTS function returns true (-1) once a screen has been created.
Syntax
- screenReady%% = _SCREENEXISTS
Description
- Function returns true (-1) once a program screen is available to use or change.
- Can be used to avoid program errors because a screen was not ready for input or alterations.
- Use before _TITLE, _SCREENMOVE and other functions that require the output window to have been created.
Examples
- Example
- Waiting in a loop until the screen exists to add the title. The _LIMIT prevents the loop from using all CPU time while waiting.
SCREEN 12 DO: _LIMIT 10: LOOP UNTIL _SCREENEXISTS _TITLE "My Title" |
See also