c++ - C++-继承时的段错误

我的示例很简单，当我使用继承(class NapanaApplication : public QGuiApplication)时崩溃，但是当直接使用QGuiApplication时，它不会崩溃并且可以正常工作。

代码完全如下所示，NapanaApplication不执行任何操作，仅继承自QGuiApplication。

怎么了？

解决:我找到了一个原因。这是因为QGuiApplication将argc作为引用，但NapanaApplication构造函数却没有。它不会产生任何错误，但是会导致QGuiApplication使用某个临时argc变量而不是main中的变量进行操作。

main.cpp

#include "napanaapplication.h"
#include "napanawindow.h"

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

    /*NapanaApplication app(argc, argv);*/ // segmentation fault

    QGuiApplication app(argc, argv); // no error

    NapanaWindow win;

    win.resize(800, 600);
    win.show();

    return app.exec();
}

napanaapplication.h

#ifndef NAPANAAPPLICATION_H
#define NAPANAAPPLICATION_H

#include <QGuiApplication>

class NapanaApplication : public QGuiApplication
{

    Q_OBJECT

public:
    explicit NapanaApplication(int argc, char* argv[]);
signals:

public slots:
};

#endif // NAPANAAPPLICATION_H

napanapplication.c

#include "napanaapplication.h"

NapanaApplication::NapanaApplication(int argc, char* argv[]) : QGuiApplication(argc, argv) {}

调试器的输出:在strlen中调用QString::fromLocal8Bit时崩溃。 调用char*的strlen指针具有值0x21，我不明白为什么，它可能应该是argv中的值。

0   strlen  /usr/lib/debug/lib/x86_64-linux-gnu/libc-2.19.so    106 0x7ffff65c0aea
1   QString::fromLocal8Bit  qstring.h   534 0x7ffff7142c11
2   QCoreApplication::arguments qcoreapplication.cpp    2254    0x7ffff738503d
3   sm_performSaveYourself  qxcbsessionmanager.cpp  188 0x7ffff05f5e3a
4   sm_saveYourselfCallback qxcbsessionmanager.cpp  171 0x7ffff05f5cc9
5   _SmcProcessMessage          0x7ffff014ad37
6   IceProcessMessages          0x7fffeff3b8c7
7   QSmSocketReceiver::socketActivated  qxcbsessionmanager.cpp  322 0x7ffff05f67e0
8   QSmSocketReceiver::qt_static_metacall   qxcbsessionmanager.moc  68  0x7ffff05f6f88
9   QMetaObject::activate   qobject.cpp 3718    0x7ffff73c097e
10  QMetaObject::activate   qobject.cpp 3583    0x7ffff73c016c
11  QSocketNotifier::activated  moc_qsocketnotifier.cpp 134 0x7ffff7458376
12  QSocketNotifier::event  qsocketnotifier.cpp 296 0x7ffff73cb4db
13  QCoreApplicationPrivate::notify_helper  qcoreapplication.cpp    1093    0x7ffff7382872
14  QCoreApplication::notify    qcoreapplication.cpp    1038    0x7ffff7382554
15  QGuiApplication::notify qguiapplication.cpp 1537    0x7ffff77f3076
16  QCoreApplication::notifyInternal    qcoreapplication.cpp    965 0x7ffff738245e
17  QCoreApplication::sendEvent qcoreapplication.h  224 0x7ffff7386087
18  socketNotifierSourceDispatch    qeventdispatcher_glib.cpp   101 0x7ffff73f6afe
19  g_main_context_dispatch         0x7ffff4f8dbd4
20  ??          0x7ffff4f8de18
21  g_main_context_iteration            0x7ffff4f8debc
22  QEventDispatcherGlib::processEvents qeventdispatcher_glib.cpp   418 0x7ffff73f7799
23  QPAEventDispatcherGlib::processEvents   qeventdispatcher_glib.cpp   115 0x7ffff0648906
24  QEventLoop::processEvents   qeventloop.cpp  128 0x7ffff737f0b2
25  QEventLoop::exec    qeventloop.cpp  204 0x7ffff737f373
26  QCoreApplication::exec  qcoreapplication.cpp    1229    0x7ffff7382b36
27  QGuiApplication::exec   qguiapplication.cpp 1528    0x7ffff77f3026
28  main    main.cpp    13  0x40275a

最佳答案

Note the signature of QGuiApplication:

QGuiApplication(int & argc, char ** argv)

您的函数改用int argc。我认为当整数值被父类构造函数视为引用时，您正在引起段错误。

关于c++ - C++-继承时的段错误，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/33271398/