Cannot compile code against qt4

[publicus]

Hello, I'm running ArchLinux and recently installed Qt4 and Qt5. However, the tutorial that I'm going through requires Qt4.

Here is my code.
[code]#include <QApplication>
#include <QWidget>

int main(int argc, char * argv[])
{
QApplication app(argc, argv);

QWidget window;

window.resize(250, 150);
window.setWindowTitle("Simple example");
window.show();

return app.exec();
}[/code]

I then did the following:
[code]% qmake -project
% qmake
% make[/code]

And this is what I got:
[code]g++ -c -pipe -march=i686 -mtune=generic -O2 -pipe -fstack-protector --param=ssp-buffer-size=4 -Wall -W -D_REENTRANT -fPIE -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_CORE_LIB -I/usr/lib/qt/mkspecs/linux-g++ -I. -I. -I/usr/include/qt -I/usr/include/qt/QtGui -I/usr/include/qt/QtCore -I. -o hello_world.o hello_world.cpp
hello_world.cpp:3:24: fatal error: QApplication: No such file or directory
#include <QApplication>
^
compilation terminated.
Makefile:298: recipe for target 'hello_world.o' failed
make: *** [hello_world.o] Error 1[/code]

How do I point to the correct headers/libraries?

[publicus]

I got it! I used the tool qtchooser to run qmake so that when the Makefile is generated, it's generated with Qt4 in mind. The process was something like this:
[code]qmake -project && qtchooser -run-tool=qmake -qt=4 && make[/code]

[SGaist]

Hi and welcome to devnet,

You should be able to go through the same tutorial using Qt 5 with some minor modifications like

@QT += widgets@

when using widgets in your application (the error you are currently getting using Qt 5's qmake)

In between, and since you found a solution (thanks for sharing by the way) please update the thread title prepending [solved] so other forum users may know a solution has been found :)