对"vtable for DigitalClock"的未定义引用 - 未定义对"DigitalClock：：staticMetaObject"的引用 - Qt

undefined reference to `vtable for DigitalClock' - undefined reference to `DigitalClock::staticMetaObject' - Qt

本文关键字：引用 未定义 DigitalClock Qt staticMetaObject for vtable      更新时间：2023-10-16
anisha@linux-dopx:~/Desktop/notes/pomodoro> ls
timer.cpp
anisha@linux-dopx:~/Desktop/notes/pomodoro> qmake -project
anisha@linux-dopx:~/Desktop/notes/pomodoro> qmake
anisha@linux-dopx:~/Desktop/notes/pomodoro> make
g++ -c -m64 -pipe -O2 -Wall -W -D_REENTRANT -DQT_NO_DEBUG -DQT_GUI_LIB -DQT_CORE_LIB -DQT_SHARED -I../../../qtsdk-2010.05/qt/mkspecs/linux-g++-64 -I. -I../../../qtsdk-2010.05/qt/include/QtCore -I../../../qtsdk-2010.05/qt/include/QtGui -I../../../qtsdk-2010.05/qt/include -I. -I. -o timer.o timer.cpp
g++ -m64 -Wl,-O1 -Wl,-rpath,/home/anisha/qtsdk-2010.05/qt/lib -o pomodoro timer.o    -L/home/anisha/qtsdk-2010.05/qt/lib -lQtGui -L/home/anisha/qtsdk-2010.05/qt/lib -L/usr/X11R6/lib64 -lQtCore -lpthread 
timer.o: In function `DigitalClock::DigitalClock(QWidget*)':
timer.cpp:(.text+0x151): undefined reference to `vtable for DigitalClock'
timer.cpp:(.text+0x159): undefined reference to `vtable for DigitalClock'
timer.cpp:(.text+0x1bc): undefined reference to `DigitalClock::staticMetaObject'
timer.o: In function `main':
timer.cpp:(.text+0x2c0): undefined reference to `vtable for DigitalClock'
timer.cpp:(.text+0x2c9): undefined reference to `vtable for DigitalClock'
timer.cpp:(.text+0x30f): undefined reference to `vtable for DigitalClock'
timer.cpp:(.text+0x318): undefined reference to `vtable for DigitalClock'
collect2: ld returned 1 exit status
make: *** [pomodoro] Error 1

我 pomodoro.pro：

######################################################################
# Automatically generated by qmake (2.01a) Tue Feb 14 10:32:09 2012
######################################################################
TEMPLATE = app
TARGET = timer
DEPENDPATH += .
INCLUDEPATH += .
# Input
SOURCES += timer.cpp

我的计时器.cpp：

#include <QLCDNumber>
#include <QtGui>
#include <QApplication>
class DigitalClock : public QLCDNumber
{
    Q_OBJECT
    public:
        DigitalClock (QWidget *parent = 0);
    private slots:
        void showTime();
};
DigitalClock :: DigitalClock (QWidget *parent) : QLCDNumber (parent)
{
    setSegmentStyle(Filled);
    QTimer *timer = new QTimer(this);
    connect (timer, SIGNAL(timeout()), this, SLOT(showTime()));
    timer->start (1000);
    showTime();
    setWindowTitle (tr ("Digital Clock"));
    resize (150, 60);
}
void DigitalClock :: showTime()
{
    QTime time = QTime::currentTime();
    QString text = time.toString("hh:mm");
    if ((time.second() % 2) == 0)
        text[2] = ' ';
    display(text);
}
int main (int argc, char *argv[])
{
    QApplication app(argc, argv);
    DigitalClock clock;
    clock.show();
    return app.exec();
}

Put 

class DigitalClock : public QLCDNumber
{
    Q_OBJECT
    public:
        DigitalClock (QWidget *parent = 0);
    private slots:
        void showTime();
};

在单独的头文件中，并将其包含在 CPP 中。不要忘记像这样将头文件名放在项目文件中

标头 += \ 数字时钟.h

宏Q_OBJECT不会在一个文件中工作。希望对您有所帮助。

此错误主要是因为您可能给出了错误的引用。

  1. 检查您是否添加了程序中所需的所有标头
  2. 检查 pri 文件
  3. 检查您是否尝试为具有单例对象的类创建对象

即，如果您创建了一个单例对象，则不允许创建对象。例：

//JSONDataManager class having singleton object
JSONDataManager* JSONDataManager::instance = 0;
JSONDataManager* JSONDataManager::Instance() {
    if (instance == 0) {
        instance = new JSONDataManager;
    }
    return instance;
}
//You can access its members as follows
JSONDataManager::Instance()->method();

//You cannot do as follows
JSONDataManager jsonManager;
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