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36 lines
967 B
Plaintext
36 lines
967 B
Plaintext
{{QBDLDATE:07-31-2022}}
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{{QBDLTIME:23:39:48}}
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{{DISPLAYTITLE:_SCREENEXISTS}}
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The [[_SCREENEXISTS]] function returns true (-1) once a screen has been created.
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{{PageSyntax}}
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: {{Parameter|screenReady%%}} = [[_SCREENEXISTS]]
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{{PageDescription}}
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* Function returns true (-1) once a program screen is available to use or change.
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* Can be used to avoid program errors because a screen was not ready for input or alterations.
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** Use before [[_TITLE]], [[_SCREENMOVE]] and other functions that require the output window to have been created.
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{{PageExamples}}
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;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.
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{{CodeStart}}
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{{Cl|SCREEN}} 12
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{{Cl|DO}}: {{Cl|_LIMIT}} 10: {{Cl|LOOP}} {{Cl|UNTIL}} {{Cl|_SCREENEXISTS}}
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{{Cl|_TITLE}} "My Title"
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{{CodeEnd}}
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{{PageSeeAlso}}
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* [[_FULLSCREEN]]
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* [[_SCREENIMAGE]]
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* [[$CONSOLE]]
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* [[$RESIZE]]
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{{PageNavigation}}
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[[Category:Final]]
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