SIGABRT在简单的消息框Qt程序中

Question

运行以下问题时出错：

@echo off

ping 8.8.4.4>c:\data.txt

FOR /F "tokens=3 delims= " %%A IN (c:\data.txt) DO SET SENTPACKETS=%%A
ECHO Packets sent: %SENTPACKETS%

FOR /F "tokens=7 delims= " %%A IN (c:\data.txt) DO SET RECEIVEDPACKETS=%%A
ECHO Packets received: %RECEIVEDPACKETS%

FOR /F "tokens=10 delims= " %%A IN (c:\data.txt) DO SET LOSTPACKETS=%%A
ECHO Packets lost: %LOSTPACKETS%

FOR /F "tokens=4 delims=,m " %%A IN (c:\data.txt) DO SET MINIMUMLATENCY=%%A
ECHO Minimum latency: %MINIMUMLATENCY%

FOR /F "tokens=9 delims=,m " %%A IN (c:\data.txt) DO SET MAXIMUMLATENCY=%%A
ECHO Maximum latency: %MAXIMUMLATENCY%

FOR /F "tokens=13 delims=,m " %%A IN (c:\data.txt) DO SET AVERAGELATENCY=%%A
ECHO Average latency: %AVERAGELATENCY%

pause

错误是：

该程序在#include <QMessageBox> #include <QApplication> int main() { QApplication app(); QMessageBox msgBox(QMessageBox::Critical, QObject::tr("text1"), QObject::tr("text2"), QMessageBox::Ok); msgBox.exec(); return 0; }

处中断

调用堆栈是：

编辑：即使我在名为QMessageBox msgBox(...);的XTerm窗口中添加了QApplication实例，我也会看到以下内容：

  

QWidget：必须在QWidget之前构建QApplication

Answer 1

该行

QApplication app();

没有创建QApplication对象 - 它实际上声明了一个不带参数的函数并返回QApplication！这有时被称为＆＃34; most vexing parse＆＃34;。

要实际构建应用程序对象，需要提供程序的参数：

    QApplication app(argc, argv);

然后是完整的程序

#include <QMessageBox>
#include <QApplication>
int main(int argc, char **argv) {
    QApplication app(argc, argv);
    QMessageBox msgBox(QMessageBox::Critical,
                       QObject::tr("text1"),
                       QObject::tr("text2"),
                       QMessageBox::Ok);
    msgBox.exec();
    return 0;
}