問題描述

我試圖創建一個簡單的控制臺應用程序來試用 Qt 的 XML 解析器.我在VS2008開始了一個項目，得到了這個模板:

I was trying to create a simple console application to try out Qt's XML parser. I started a project in VS2008 and got this template:

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    return a.exec();
}

因為我不需要事件處理，所以我想知道如果我忽略創建一個 QCoreApplication 并運行事件循環，我是否會遇到麻煩.文檔說明在大多數情況下建議使用它.

Since I don't need event processing, I was wondering whether I may get into trouble if I neglect to create a QCoreApplication and running the event loop. The docs state that it's recommended in most cases.

然而，出于好奇，我想知道如何在事件循環上執行一些通用任務，然后終止應用程序.我無法用谷歌搜索相關示例.

For the sake of curiosity however, I am wondering how could I make some generic task execute on the event loop and then terminate the application. I was unable to google a relevant example.

推薦答案

如果您希望事件循環運行，這里有一種簡單的方法可以構建應用程序.

Here is one simple way you could structure an application if you want an event loop running.

// main.cpp
#include <QtCore>

class Task : public QObject
{
    Q_OBJECT
public:
    Task(QObject *parent = 0) : QObject(parent) {}

public slots:
    void run()
    {
        // Do processing here

        emit finished();
    }

signals:
    void finished();
};

#include "main.moc"

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

    // Task parented to the application so that it
    // will be deleted by the application.
    Task *task = new Task(&a);

    // This will cause the application to exit when
    // the task signals finished.    
    QObject::connect(task, SIGNAL(finished()), &a, SLOT(quit()));

    // This will run the task from the application event loop.
    QTimer::singleShot(0, task, SLOT(run()));

    return a.exec();
}

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