error: undefined reference to `vtable for n qt出现这种问题怎么解决啊

[诣澜]

各种办法不灵，不知道怎么弄了
#include "mainwindow.h"
#include <QApplication>
#include <QtGui>
#include<QtWidgets>
class notepad:public QWidget
{
Q_OBJECT
public:
notepad();
QTextEdit *qte;
QPushButton *qpb;
QVBoxLayout *qvbl;
public slots:
void quit();
};

notepad::notepad(){

qte =new QTextEdit;
qpb=new QPushButton("退出");
connect(qpb,SIGNAL(clicked()),this,SLOT(quit()));
qvbl->addWidget(qte);
qvbl->addWidget(qpb);
setLayout(qvbl);

}

void notepad::quit(){
qApp->quit;
}

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
/* MainWindow w;
w.show();*/
notepad b;
return a.exec();
}

[fanlvlgh]

添加引用库。。

[cobra_chen]

重新编译试试？