Getting Undefined Reference Error

I am getting the error:

mainwindow.cpp:44: undefined reference to `StartWindow::StartWindow(QWidget*)

What is the reason? The code is below:

mainwindow.h

Code:

---

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
class MainArea;
class StartWindow;
 
class MainWindow : public QMainWindow
{
    Q_OBJECT
 
    public:
        MainWindow();
        ~MainWindow();
    private slots:
        void newGame();
 
    private:
 
        void setupActions();
 
        MainArea *m_graphicsViewArea;
        StartWindow *m_startWindow;
        KTextEdit *m_textArea;
 
};
 
#endif // MAINWINDOW_H

---

mainwindow.cpp

Code:

---

#include "mainwindow.h"
#include "mainarea.h"
#include "startwindow.h"
 
 
//Constructor
MainWindow::MainWindow()
    : QMainWindow()
{
 
 
    m_graphicsViewArea = new MainArea(this);
    m_startWindow = new StartWindow(this); //Here is the error
    setCentralWidget(m_startWindow);
    setWindowTitle("Mancala");
 
    setupActions();
 
}

---

startwindow.h

Code:

---

#ifndef STARTWINDOW_H
#define STARTWINDOW_H
 
class StartWindow : public QGraphicsView{
 
    Q_OBJECT
 
    public:
        StartWindow(QWidget *parent);
 
    private:
 
        QGraphicsSimpleTextItem *m_start_text;
};
 
#endif // STARTWINDOW_H

---

startwindow.cpp

Code:

---

#include "startwindow.h"
 
StartWindow::StartWindow(QWidget *parent)
    : QGraphicsView(parent)
{
 
    m_start_text = new QGraphicsSimpleTextItem("This is a collection of Mancala Games");
 
    m_start_text->setFont( QFont("Comic Sans MS", 24, QFont::Bold) );
 
   scene()->addItem(m_start_text);
 
}

---

Mahfuz

make sure startwindow.cpp is added to your .pro file; maybe you need to run qmake again?

#include <QGraphicsView> in startwindow