when i try to develop a hello demo in QT creator with the code following :
#include<QApplication>
#include<QLabel>
int main(int argc,char *argv[])
{
QApplication app(argc,argv);
QLabel l("hello,word!");
l.show();
return app.exec();
}
the IDE inform me that "QApplication no such file or directory", then i search the Internet, and find that i should add the following code in "*.pro":
QT += core gui widgets
or add the following:
QT += core gui
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
these code tell the qmake to include the header.