C1083: Cannot open include file: 'QApplication' [SOLVED]

[Muhammad]

I created a very simple project using "Empty Qt project" from Qt Creator.
Then I added my files to the project.

Here is the .pro file

@CONFIG += qt
SOURCES +=
main.cpp
hello.cpp

HEADERS +=
hello.h@

and here is the .h file

@#include <QPushButton>
class MyPushButton : public QPushButton
{
public:
MyPushButton(const QString &text);
};
@

and here is the .cpp file
@#include <QDebug>
#include "hello.h"

MyPushButton::MyPushButton(const QString &text)
: QPushButton(text)
{
setObjectName("mypushbutton");
qDebug() << "My PushButton has been constructed";
}
@

and here is the main file
@#include <QApplication>
#include "hello.h"

int main(int argc, char **argv)
{
QCoreApplication app(argc, argv);

MyPushButton helloButton("Hello world!");
helloButton.resize(100, 30);

helloButton.show();
return app.exec();

}
@

when I run the project I get the errors
C1083: Cannot open include file: 'QApplication' No such file or directory
C1083: Cannot open include file: 'QPushButton' No such file or directory

I added this line to the .pro file
@ QT += widgets @

and rerun qmake and rebuild

When I run again I get no errors but the I get this
The program has unexpectedly finished.
and then nothing happens
So please HELP

[amccarthy]

You are instantiating a QCoreApplication. For a widget based application you should be using a QApplication.

[andre]

And, for that to work properly, make sure you have this in your .pro file:
@
qt *= core gui widgets
@

[Muhammad]

Thank you everybody, It was like amccarthy said.