C++ C++；-继承时的分段错误_C++_Qt

C++ C++；-继承时的分段错误

c++ qt

C++ C++；-继承时的分段错误,c++,qt,C++,Qt,我的示例非常简单，当我使用继承时（classnapanaapplication:publicqguiapplication）会崩溃，但在直接使用QGuiApplication时不会崩溃并正常工作代码如下所示，napana应用程序没有做任何事情，只是从qgui应用程序继承怎么了解决：我找到了一个原因。这是因为QGuiApplication将argc作为参考，但NapanaApplication构造函数没有。它不会生成任何错误，但会导致qgui应用程序使用一些临时argc变量而不是main中的

我的示例非常简单，当我使用继承时（

classnapanaapplication:publicqguiapplication

）会崩溃，但在直接使用

QGuiApplication

时不会崩溃并正常工作

代码如下所示，

napana应用程序

没有做任何事情，只是从

qgui应用程序

继承

怎么了

解决：我找到了一个原因。这是因为

QGuiApplication

将

argc

作为参考，但

NapanaApplication

构造函数没有。它不会生成任何错误，但会导致

qgui应用程序

使用一些临时

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

调试器的输出：在
QString:：fromLocal8Bit
中调用
strlen
时，调用
strlen
的
char*
指针上有值
0x21
，我不明白为什么，它可能来自
argv

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
:
您的函数改为
int argc
。当父类构造函数将整数值视为引用时，我认为您导致了SEGFULT。
:

您的函数改为
int argc
。我认为，当父类构造函数将整数值视为引用时，您导致了SEGFULT。
崩溃的原因是什么？@Surt:segmentation fault（Signal SIGSEGV）崩溃的原因是什么？@Surt:segmentation fault（Signal SIGSEGV）ooo。那就行了。错误的数字会导致错误的参数数量，导致未终止的字符数组上出现
strlen
。@user4581301有点奇怪，它只有在通过
app.exec（）
启动事件循环时才会发生？我猜Qt在此之前没有检查一些参数。我查看了源代码，这是因为Qt也将argc存储为引用，所以它们在构造函数QtConstructor（int&argcc）：argc（argcc）中初始化它。如果他们将其存储为普通int，则不会发生任何事情。那就行了。错误的数字会导致错误的参数数量，导致未终止的字符数组上出现
strlen
。@user4581301有点奇怪，它只有在通过
app.exec（）
启动事件循环时才会发生？我猜Qt在此之前没有检查一些参数。我查看了源代码，这是因为Qt也将argc存储为引用，所以它们在构造函数QtConstructor（int&argcc）：argc（argcc）中初始化它。如果他们将其存储为正常int，则不会发生任何事情。
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

QGuiApplication(int & argc, char ** argv)