相关疑难解决方法(0)

我在Windows 7 Ultimate 32位上使用Qt Creator 2.0.1和Qt 4.7.0(32位).

请考虑以下代码,这是产生错误的最小代码:

class T : public QObject, public QGraphicsItem
{
    Q_OBJECT

public:
    T() {}

    QRectF      boundingRect() const {return QRectF();}
    void        paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
                      QWidget *widget) {}
};

int main()
{
    T t;
    return 0;
}

上面的代码片段导致以下链接器错误:

在函数"T"中:

未定义引用`vtable for T'

未定义引用`vtable for T'

在函数`~T'中:

未定义引用`vtable for T'

未定义引用`vtable for T'

如果我注释掉包含的行Q_OBJECT,它编译得很好.我需要信号和插槽,QGraphicsItem所以我需要Q_OBJECT.

代码有什么问题？谢谢.

这是我的标题:

#ifndef BARELYSOCKET_H
#define BARELYSOCKET_H

#include <QObject>
//! The First Draw of the BarelySocket!

class BarelySocket: public QObject
{
    Q_OBJECT

public:
    BarelySocket();
public slots:
    void sendMessage(Message aMessage);
signals:
    void reciveMessage(Message aMessage);

private:
    //   QVector<Message> reciveMessages;
};

#endif // BARELYSOCKET_H

这是我的班级:

#include <QTGui>
#include <QObject>
#include "type.h"
#include "client.h"
#include "server.h"

#include "barelysocket.h"

BarelySocket::BarelySocket()
{
    //this->reciveMessages.clear();
    qDebug("BarelySocket::BarelySocket()");
}

void BarelySocket::sendMessage(Message aMessage)
{
}

void BarelySocket::reciveMessage(Message aMessage)
{
}

我收到链接器错误:

undefined reference to 'vtable for BarelySocket'

• 这意味着我有一个未实现的虚方法.但我班上没有虚拟方法.
• 我评论出矢量认为它是原因,但错误并没有消失.
• 这Message是一个复杂的struct …

以下链接示例:http://developer.kde.org/documentation/books/kde-2.0-development/ch03lev1sec3.html

#include <QObject>
#include <QPushButton>
#include <iostream>
using namespace std;

class MyWindow : public QWidget
{
    Q_OBJECT  // Enable slots and signals
    public:
        MyWindow();
    private slots:
        void slotButton1();
        void slotButton2();
        void slotButtons();
    private:
        QPushButton *button1;
        QPushButton *button2;
};

MyWindow :: MyWindow() : QWidget()
{
    // Create button1 and connect button1->clicked() to this->slotButton1()
    button1 = new QPushButton("Button1", this);
    button1->setGeometry(10,10,100,40);
    button1->show();
    connect(button1, SIGNAL(clicked()), this, SLOT(slotButton1()));

    // Create button2 and connect button2->clicked() to this->slotButton2()
    button2 = new QPushButton("Button2", this);
    button2->setGeometry(110,10,100,40); …

我正在尝试编写一个基本上像indianwebproxy一样工作的Http代理

所以我启动了qtcreator,但是我的一个类无法使用臭名昭着的错误进行编译:undefined reference to vtable for HttpProxyThreadBrowser.我无法弄清楚为什么这样做.我在Stackoverflow上阅读了类似的问题,显然问题是未定义的虚拟方法不纯,但我还没有声明任何虚函数.这是我的课

class HttpProxyThreadBrowser : public QThread
{
public:
    HttpProxyThreadBrowser(QTcpSocket outgoingSocket,QTcpSocket  browserSocket,QObject *parent = 0);
    ~HttpProxyThreadBrowser(){};
    void run();

private:
    QTcpSocket outgoingSocket;
    QTcpSocket browserSocket;

};

我在这里用pastebin定义了这个类,以免给你带来烦恼.不幸的是,我无法找出为什么vtable未定义.请协助.

httpproxythreadbrowser.cpp:5: undefined reference to `vtable for HttpProxyThreadBrowser
collect2: ld returned 1 exit status