Problem with Mdiarea Subwindow

matobodo

I have these files:
main.cpp mainwindow.cpp .h .ui dialog.cpp .h. 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&#40;&#41;;

}
@

mainwindow.h
@#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include "dialog.h"

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
Q_OBJECT

public:
explicit MainWindow(QWidget *parent = 0);
~MainWindow();
Dialog *dialog;

private slots:
void on_pushButton_clicked();

void on_pushButton_2_clicked();

private:
Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H
@
mainwindow.cpp
@#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
}

MainWindow::~MainWindow()
{
delete ui;
}

void MainWindow::on_pushButton_clicked()
{
if (!dialog)
{
dialog = new Dialog(this);
ui->mdiArea->addSubWindow(dialog,Qt::Dialog);
}
dialog->show();
dialog->adjustSize();
}

void MainWindow::on_pushButton_2_clicked()
{
}
@

The problem is when i click the pushButton, the dialog appear in Mdiarea. Then i close the dialog and when i click again pushButton aplication crash.

SGaist

Hi,

You're lucky it doesn't crash directly, you don't initialize dialog to 0 in your constructor.

matobodo

So how can i solve the problem?

SGaist

Start by initializing dialog to 0 in the constructor

matobodo

i am noob. can you please show me the code, because i dont know how to do it

SGaist

You don't know how to initialize a member variable in C++ ?

Then you should rather grab a good C++ book and read it before continuing.

matobodo

i know how to initialize the variable, but sometimes my english isn't good enough to understand what am i reading

SGaist

So it's alright now ?