(C++) Cannot create a QWidget when no GUI is being used

 

Runtime error.

 

 

 

 

 

Full error message

 

 

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Starting /MyFolder/mymain.cpp... QWidget: Cannot create a QWidget when no GUI is being used The program has unexpectedly finished. /MyFolder/mymain exited with code 0

 

 

 

 

 

Cause

 

Operating system: Ubuntu 10.04 LTS Lucid Lynx

IDE: Qt Creator 2.0.0

Project type: GUI Application

Compiler: G++ 4.4.1

Libraries used:

• Qt: version 4.7.0 (32 bit)

 

 

 

 

 

Qt project file

 

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#------------------------------------------------- # # Project created by QtCreator 2010-07-24T12:32:57 # #------------------------------------------------- QT += core gui TARGET = CppRuntimeErrorCannotCreateAqwidgetWhenNoGuiIsBeingUsed TEMPLATE = app SOURCES += main.cpp

 

 

 

 

 

Source code

 

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#include <QtCore/QCoreApplication> #include <QDialog> int main(int argc, char *argv[]) {   QCoreApplication a(argc, argv);   QDialog d;   d.show();   return a.exec(); }

 

• Download the Qt Creator project 'CppRuntimeErrorCannotCreateAqwidgetWhenNoGuiIsBeingUsed' (zip)

 

 

 

 

 

Solution

 

Do not use QCoreApplication, but use QApplication instead.

 

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#include <QApplication> #include <QDialog> int main(int argc, char *argv[]) {   QApplication a(argc, argv);   QDialog d;   d.show();   return a.exec(); }