使用while循环时不出现窗口 [英] Window doesn't appear when using while loop

问题描述

我正在用 C++ 用 QT 做一些东西.

I am making something in QT in C++.

但是，当我在代码中使用 while(1) 循环时，该窗口永远不会出现.我尝试了很多方法，例如在循环末尾添加 QApplication::processEvents(); ，但它不起作用.没有窗户.

However, when I am using a while(1) loop in the code, the window never appears. I tried many things, such as adding a QApplication::processEvents(); at the end of the loop, but it doesn't work. There is no window.

如何让窗口出现?

示例代码:

MainWindow::MainWindow(QWidget * parent, Qt::WindowFlags flags) : QMainWindow(parent, flags) {
    _ui.setupUi(this);

while(1){
}

}

谢谢

推荐答案

每个小部件构造函数都不应阻塞主消息循环！

Every widget constructor should never block the main message loop!

主消息循环通常如下所示:

The main message loop looks usually like this:

int main(int argc, char *argv[]) {
    QApplication a(argc, argv);
    MainWindow w(nullptr);
    w.show();
    int r = a.exec();
    return r
}

在你的情况下，你的 MainWindow ctor 永远不会返回，所以 w.show() 永远不会被调用并且 a.exec() (mainmessgae 循环)永远不会执行.

In your case your MainWindow ctor never returns, so w.show() is never called and a.exec() (main messgae loop) is never executed.

不仅阻塞可能是主窗口构造函数中的一个问题，而且在主消息循环执行之前生成的信号也永远不会被引发.例如，在主窗口 ctor 中建立 TCP/IP 连接将永远不会引发 connected() 信号和关联的插槽.*1

Not only blocking may be a problem in main window ctor, but also signals that are generated before main message loop is executed gets never raised. For an example establishment of an TCP/IP connection within main window ctor will never raise the connected() signal and associated slots. *1

至少如果主窗口的创建是在主消息循环执行之前，就像在 99% 的情况下一样.

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