Question

When I compile my program, I get ld returned 1 exit status error. Here is the code (main.cpp):

#include <QtGui/QApplication>
#include <QPushButton>
#include <QHBoxLayout>
#include <QLineEdit>
#include "widget.h"

int main(int argc, char *argv[])
{
QApplication app(argc, argv);

QPushButton *okayButtom = new QPushButton("Okay");

QMainWin *mainWin = new QMainWin("Say Pig!");
QHBoxLayout *Hbox = new QHBoxLayout;
QLineEdit *inputBox = new QLineEdit;


mainWin->setWindowTitle("Hello, Pig!");
Hbox->addWidget(inputBox);
Hbox->addWidget(okayButtom);

mainWin->setLayout(Hbox);
mainWin->show();

return app.exec();
}

and this is widget.h

#ifndef WIDGET_H
#define WIDGET_H

#include <QtGui>

class QMainWin : public QWidget
{
Q_OBJECT
private:
QString WinTitle;
public:
QMainWin(const QString &title, QWidget *parent = 0):WinTitle(title)
{
    this->setWindowTitle(WinTitle);
}

~QMainWin();
};

#endif // WIDGET_H

I didn’t use UI file, I only use cpp source file.

Answer 1

• define a body for the destructor or remove the declaration ~QMainWin();
• remove the macros Q_OBJECT;
• add QWidget(parent) to the initializing list at the
  constructor.

read this http://doc.trolltech.com/4.3/tutorial-t4.html