right way to open a new window

First when the application start I display the login screen. Then after successful login i have to display the main window. What is the right way to close the login screen and display the main window?

At the moment i have something like this:

Code:

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main_window *main = new main_window();			
this->close(); // close login			
main->show();	// show main

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When i call main_window *main = new main_window(this), then the application is not working right.

I have searched Qt examples & demos but all use just one window.

Look at the following code
Will give you a basic Idea

Code:

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int main( ... ) {
    LoginDialog *loginDlg = new LoginDlg;
 
    if(  loginDlg->exec() != Qt:;Accepted ) {
         return 0;
    }
 
    //check the login Info 
    delete  loginDlg;
 
    MainWindow w;
    w.show()
    return app.exec();
}

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