一个奇怪的问题(画面未显示) [复制链接]

我在Qt example（phonon，qmusicplayer）中加了一个login画面，在login画面按下确认按钮后，显示qmusicplayer的画面，但是qmusicplayer画面一闪就未出现，代码如下
int main(int argv, char **args)
{
    QApplication app(argv, args);
    app.setApplicationName("Music Player");
    app.setQuitOnLastWindowClosed(true);

     Login login;
    login.show();
    return app.exec();
}
Login::Login()
{
    QHBoxLayout* hlayerout = new QHBoxLayout();

    QLabel* label = new QLabel("name:  ");
    QLineEdit* nameedit = new QLineEdit();
    hlayerout->addStretch();
    hlayerout->addWidget(label);
    hlayerout->addWidget(nameedit);

    QHBoxLayout* hlayerout1 = new QHBoxLayout();
    QLabel* label1 = new QLabel("password:  ");
    QLineEdit* nameedit1 = new QLineEdit();
    hlayerout1->addStretch();;
    hlayerout1->addWidget(label1);
    hlayerout1->addWidget(nameedit1);

    QHBoxLayout* hlayerout2 = new QHBoxLayout();
    QPushButton* confirmbutton = new QPushButton("Ok");
    QPushButton* cancelbutton = new QPushButton("Cancel");
    hlayerout2->addStretch();;
    hlayerout2->addWidget(confirmbutton);
    hlayerout2->addWidget(cancelbutton);

    QVBoxLayout *mainLayout = new QVBoxLayout;
    mainLayout->addLayout(hlayerout);
    mainLayout->addLayout(hlayerout1);
    mainLayout->addLayout(hlayerout2);
    mainLayout->setSpacing(0);

    setLayout(mainLayout);
  
    connect(confirmbutton,SIGNAL(clicked()),this,SLOT(slotShowWindow()));
}

void Login::slotShowWindow()
{
    close();
    MainWindow window;
    window.show();
}

slotShowWindow()槽函数创建的局部变量window在该函数执行完毕之后就立即销毁了，当然看不到了。解决办法如下：
把window设置为模态窗口，或者用exec函数替换show函数，这样window窗口就会消息循环的原因停留在那里，直到关闭。
另外一个解决办法就是在Login的类中加一个MainWindow成员指针，并在构造函数中创建它，用的时候show，不用的时候就hide

谢谢

Always use new to allocate memory(heap memory) for Qt components.