通常指针导致分段错误 [英] Usual pointer causing Segmentation Fault

问题描述

我的班级ComponentArea如下所示：

My class "ComponentArea" looks like this:

#ifndef COMPONENTAREA_H
#define COMPONENTAREA_H

#include <QObject>
#include <QWidget>
#include <QScrollArea>
#include <QtDesigner/QtDesigner>
#include <QMouseEvent>
#include <QPainter>

#include <Components/Sockets/socket.h>
class Socket;

class ComponentArea : public QScrollArea
{
    Q_OBJECT

    public:
        ComponentArea(QWidget* parent);

        void connectSockets(Socket* a, Socket* b);
        void childBlock_childSocket_mousePressEvent(Socket* sender, QMouseEvent* event);
        void childBlock_childSocket_mouseReleaseEvent(Socket* sender, QMouseEvent* event);

    private:
        Socket* pressedSocket;

        void mouseReleaseEvent(QMouseEvent *event);
};

#endif // COMPONENTAREA_H

在构造函数中，我将pressedSocket设置为0：

In the constructor, I set pressedSocket to 0:

pressedSocket = 0;

每当我尝试使用pressedSocket时，在其中一个事件中，我会遇到分段错误：

Whenever I try to use pressedSocket, in one of the events, I get a Segmentation Fault:

void ComponentArea::childBlock_childSocket_mousePressEvent(Socket *sender, QMouseEvent *event)
{
    if((pressedSocket == 0) && (event->button() == Qt::LeftButton)) //SIGSEGV here
    {
        pressedSocket = sender;
    }
}

当我尝试在此行检查pressedSocket时，调试器告诉我pressedSocket< ;没有这样的价值>。



我看不出我做错了什么。有什么建议吗？在此先感谢！

When I try to inspect pressedSocket at this line, the Debugger tells me "pressedSocket <no such value>".

I don't see what I am doing wrong. Any advices? Thanks in advance!

推荐答案

我的猜测是你的ComponentArea对象不存在（还）。看看你分配该对象的位置。因此，this指针可能指向nirwana然后访问任何成员将导致分段错误。

My guess is that your ComponentArea object does not exist (yet). Take a look where you allocate that object. Hence, the this pointer is probably pointing into nirwana and then the access to any member will cause a segmentation fault.

最后我想出了对另一个类中的ComponentView的引用，我打电话给事件，没有分配。因此，我能够调用该事件，但没有pressSocket存在。

Finally I figured out that a reference to the ComponentView in another class, from which I called the event, was not assigned. Therefore, I was able to call the event, but there was no pressedSocket existent.

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