qb64/internal/help/_SCREENEXISTS.txt

{{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 have been created.


{{PageExamples}}
''Example:'' The loop busy-waits until the screen exists to add the title.
{{CodeStart}} '' ''
{{Cl|SCREEN}} 12
{{Cl|DO}}: {{Cl|LOOP}} {{Cl|UNTIL}} _{{Cl|SCREENEXISTS}}
{{Cl|_TITLE}} "My Title"
{{CodeEnd}}


{{PageSeeAlso}}
* [[_FULLSCREEN]]
* [[_SCREENIMAGE]]
* [[$CONSOLE]]
* [[$RESIZE]]


{{PageNavigation}}