Getting runtime errors with QWebPage - c++

Question

I have created a Qt GUI application but I haven't touched anything regarding the GUI. I have modified mainwindow.cpp and the project file.
mainwindow.cpp:
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QWebPage>
#include <QWebFrame>
QWebPage page;
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
connect(page.mainFrame(), SIGNAL(loadFinished(bool)), this, SLOT(pageLoaded1(bool)));
QUrl router("http://192.168.1.1");
page.mainFrame()->load(router);
}
MainWindow::~MainWindow()
{
delete ui;
}
untitled.pro:
#-------------------------------------------------
#
# Project created by QtCreator 2013-05-01T23:48:00
#
#-------------------------------------------------
QT += core gui webkit webkitwidgets
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
TARGET = untitled
TEMPLATE = app
SOURCES += main.cpp\
mainwindow.cpp
HEADERS += mainwindow.h
FORMS += mainwindow.ui
main.cpp:
#include "mainwindow.h"
#include <QApplication>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
MainWindow w;
w.show();
return a.exec();
}
Error:
---------------------------
Microsoft Visual C++ Debug Library
---------------------------
Debug Error!
Program: ...tled-Desktop_Qt_5_0_2_MSVC2010_32bit-Debug\debug\untitled.exe
Module: 5.0.2
File: global\qglobal.cpp
Line: 1977
ASSERT: "!"No style available without QApplication!"" in file kernel\qapplication.cpp, line 962
(Press Retry to debug the application)
---------------------------
Abort Retry Ignore
---------------------------
Extra characters are inserted here to bypass character requirement.

Answer 1

In main.cpp, make sure you create an application object, even if you don't use directly:
QApplication app;
// Below you can then create the window
Edit
The problem is that you are creating a QWebPage as a global object, and before the QApplication has been created. To solve the problem, make the page a member of the MainWindow class. Also make the page a pointer, otherwise you will get other problems.
i.e. in mainwindow.h:
private:
QWebPage* page;
in mainwindow.cpp:
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QWebPage>
#include <QWebFrame>
// Remove this!!
// QWebPage page;
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
// Create the page here:
page = new QWebPage(this);
connect(page.mainFrame(), SIGNAL(loadFinished(bool)), this, SLOT(pageLoaded1(bool)));
QUrl router("http://192.168.1.1");
page.mainFrame()->load(router);
}
MainWindow::~MainWindow()
{
delete ui;
}