error: incomplete type 'QDate' cannot be used to name a scope

hello everyone,
i am trying to run an if statement with condition

if (QDate::isValid(year,month,day)) {do smth;}

yet i get the compiler error

dateinputform.ui.h:299:
error: incomplete type 'QDate' cannot be used to name a scope
make: *** [.obj/dateinputform.o] Error 1


i have of course #included <qdate.h> in my implementation..
why do i get this error?
thank you for your help.
nass

Quote:

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Originally Posted by nass

i have of course #included <qdate.h> in my implementation..

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Are you 100% sure? Try adding #include <qdate.h> at the top of dateinputform.ui.h.

PS. Consider using the subclassing approach.

Perhaps , <qdatetime.h>

Quote:

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Originally Posted by lum

Perhaps , <qdatetime.h>

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Right, qdate.h is in Qt4.