Qt ошибка expected class name before token

I’m getting the error «expected class-name before ‘{‘ token» in my C++ Qt project. After googling it, it seems like its a problem of circular includes. I have pawn.h that includes piece.h, which includes board.h, which completes the circle by including pawn.h. I’ve read that this can be fixed with forward declarations, but I’ve tried forward declaring a few of problem classes, and it doesn’t work.

#ifndef PAWN_H
#define PAWN_H

#include "piece.h"

class Pawn : public Piece
{
    Q_OBJECT
public:
    explicit Pawn(QWidget *parent = 0);
};

#endif // PAWN_H

.

#ifndef PIECE_H
#define PIECE_H

#include <QWidget>
#include "board.h"

class Board;
class Piece : public QWidget
{
    Q_OBJECT
public:
    explicit Piece(QWidget *parent = 0);
    void setPosition(int rank, int file);
    QPixmap pixmap;

protected:
    void paintEvent(QPaintEvent *);

private:
    int rank;
    int file;
    int x;
    int y;
};

#endif // PIECE_H

.

#ifndef BOARD_H
#define BOARD_H

#include <QWidget>
#include <QVector>
#include <QGridLayout>
#include "square.h"
#include "pawn.h"
#include "knight.h"
#include "bishop.h"
#include "queen.h"
#include "king.h"

class Board : public QWidget
{
public:
    explicit Board(QWidget *parent = 0);
    QVector < QVector<Square *> > sqrVector;
    Pawn *pawn[8];

    Knight *knight[2];

    Bishop *bishop[2];

    Queen *queen;
    King *king;

private:
    QGridLayout *layout;
};

#endif // BOARD_H

1. Expected class-name before ‘{‘ token
   

   I’ve working on my first project and I’ve hit a speed bump. When building, I get this error message. Expected class-name before ‘{‘ token in mainwindow.h line 8.

   Here is mainwindow.h:

   #ifndef MAINWINDOW_H
   #define MAINWINDOW_H
   #include "ui_mainwindow.h"
   class MainWindow : public QWidget, private Ui::MainWindowDLG
   {
   Q_OBJECT
   public:
     MainWindow(QWidget *parent = 0);
   public slots:
   
   
   
     
   
   
                          
     
   
   
   
   void display_pic();
   };
   #endif
   To copy to clipboard, switch view to plain text mode 
   

   I know it’s got to be something simple I am overlooking. Thanks in advance.

   ---

2. Re: Expected class-name before ‘{‘ token
   

   add #include <QWidget> in this file, e.g.

   #ifndef MAINWINDOW_H
   #define MAINWINDOW_H
   #include <QWidget>
   #include "ui_mainwindow.h"
   ...
   To copy to clipboard, switch view to plain text mode 
   

   Qt Assistant — rocks!
   please, use tags [CODE] & [/CODE].

   ---

3. Re: Expected class-name before ‘{‘ token
   

   ---

4. Re: Expected class-name before ‘{‘ token
   

   Qt Assistant — rocks!
   please, use tags [CODE] & [/CODE].

   ---

5. Re: Expected class-name before ‘{‘ token
   

   Attached #include <QWidget> too all other files main.cpp, mainwindow.cpp, and mainwindow.h. I think that is what you wanted me to try. Still get the same error message.

   ---

6. Re: Expected class-name before ‘{‘ token
   

   no, I was asking you to upload your sources, that I can try to compile your project by myself.

   Qt Assistant — rocks!
   please, use tags [CODE] & [/CODE].

   ---

7. Re: Expected class-name before ‘{‘ token
   

   Sorry. Here we go…

   main.cpp

   #include <QApplication>
   #include "mainwindow.h"
   int main(int argc, char *argv[])
   {
       MainWindow *dialog = new MainWindow;
       dialog->show();
   return app.exec();
   }
   To copy to clipboard, switch view to plain text mode 
   

   mainwindow.cpp

   #include "mainwindow.h"
   #include <QtGui> 
   #include <QPixmap>
   MainWindow::MainWindow(QWidget *parent)
   {
       setupUi(this);
   connect( pushButton_display, SIGNAL( clicked() ), this, SLOT( display_pic() ) );
   }
   void MainWindow::display_pic()
   {
       label_image->setPixmap(pixmap);
   }
   To copy to clipboard, switch view to plain text mode 
   

   mainwindow.h

   #ifndef MAINWINDOW_H
   #define MAINWINDOW_H
   #include <QWidget>
   #include "ui_mainwindow.h"
   class MainWindow : public QWidget, private Ui::MainWindowDLG
   {
   Q_OBJECT
   public:
     MainWindow(QWidget *parent = 0);
   public slots:
   void display_pic();
   };
   #endif
   To copy to clipboard, switch view to plain text mode 
   

   ui_mainwindow.h

   /********************************************************************************
   ** Form generated from reading ui file 'mainwindow.ui'
   **
   ** Created: Mon Jun 15 22:04:49 2009
   **      by: Qt User Interface Compiler version 4.5.1
   **
   ** WARNING! All changes made in this file will be lost when recompiling ui file!
   ********************************************************************************/
   #ifndef UI_MAINWINDOW_H
   #define UI_MAINWINDOW_H
   #include <QtCore/QVariant>
   #include <QtGui/QAction>
   #include <QtGui/QApplication>
   #include <QtGui/QButtonGroup>
   #include <QtGui/QHeaderView>
   #include <QtGui/QLabel>
   #include <QtGui/QMainWindow>
   #include <QtGui/QPushButton>
   #include <QtGui/QWidget>
   QT_BEGIN_NAMESPACE
   class Ui_MainWindow
   {
   public:
   {
   if (MainWindow->objectName().isEmpty())
               MainWindow->setObjectName(QString::fromUtf8("MainWindow"));
           MainWindow->resize(770, 524);
           MainWindow->setStyleSheet(QString::fromUtf8("background-color: rgb(136, 162, 255);n"
   ""));
           centralWidget = new QWidget(MainWindow);
           centralWidget->setObjectName(QString::fromUtf8("centralWidget"));
           label_image = new QLabel(centralWidget);
           label_image->setObjectName(QString::fromUtf8("label_image"));
           label_image->setGeometry(QRect(10, 10, 751, 461));
           label_image->setStyleSheet(QString::fromUtf8("background-color: rgba(62, 99, 255, 43);"));
           pushButton_display = new QPushButton(centralWidget);
           pushButton_display->setObjectName(QString::fromUtf8("pushButton_display"));
           pushButton_display->setGeometry(QRect(330, 480, 113, 32));
           MainWindow->setCentralWidget(centralWidget);
           retranslateUi(MainWindow);
   } // setupUi
   {
           MainWindow->setWindowTitle(QApplication::translate("MainWindow", "MainWindow", 0, QApplication::UnicodeUTF8));
           label_image->setText(QString());
           pushButton_display->setText(QApplication::translate("MainWindow", "Push Me", 0, QApplication::UnicodeUTF8));
   Q_UNUSED(MainWindow);
   } // retranslateUi
   };
   namespace Ui {
       class MainWindow: public Ui_MainWindow {};
   } // namespace Ui
   QT_END_NAMESPACE
   #endif // UI_MAINWINDOW_H
   To copy to clipboard, switch view to plain text mode 
   

   ---

8. Re: Expected class-name before ‘{‘ token
   

   try this

   mainwindow.cpp

   #include "mainwindow.h"
   #include <QtGui> 
   #include <QPixmap>
   MainWindow::MainWindow(QWidget *parent)
   {
       setupUi(this);
   connect( pushButton_display, SIGNAL( clicked() ), this, SLOT( display_pic() ) );
   }
   void MainWindow::display_pic()
   {
       label_image->setPixmap(pixmap);
   }
   To copy to clipboard, switch view to plain text mode 
   

   mainwindow.h

   #ifndef MAINWINDOW_H
   #define MAINWINDOW_H
   #include <QMainWindow>
   #include "ui_mainwindow.h"
   class MainWindow : public QMainWindow, private Ui::MainWindowDLG
   {
   Q_OBJECT
   public:
     MainWindow(QWidget *parent = 0);
   public slots:
   void display_pic();
   };
   #endif
   To copy to clipboard, switch view to plain text mode 
   

   Qt Assistant — rocks!
   please, use tags [CODE] & [/CODE].

   ---

9. Re: Expected class-name before ‘{‘ token
   

   Originally Posted by spirit
   

   MainWindow::MainWindow(QWidget *parent)
   
   To copy to clipboard, switch view to plain text mode 
   

   Hi, a short side question. I pass everytime parent to the ctor of the base class. What’s the advantage of passing this?

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10. 15th June 2009, 21:03

    
    

    #10

    Re: Expected class-name before ‘{‘ token
    

    mistyped, of course must be passed parent.

    Qt Assistant — rocks!
    please, use tags [CODE] & [/CODE].

    ---

11. 15th June 2009, 21:05

    
    

    #11

    Re: Expected class-name before ‘{‘ token
    

    Did you add the «mainwindow.ui» file to your project file and reran qmake? I guess you did… nevermind…

    Your biological and technological distinctiveness will be added to our own. Resistance is futile.

    Please ask Qt related questions on the forum and not using private messages or visitor messages.

    

    ---

12. 15th June 2009, 21:13

    
    

    #12

    Re: Expected class-name before ‘{‘ token
    

    Originally Posted by spirit
    

    mistyped, of course must be passed parent.

    Fine, than I can stop thinking about

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13. 16th June 2009, 05:26

    
    

    #13

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14. 16th June 2009, 06:18

    
    

    #14

    Re: Expected class-name before ‘{‘ token
    

    ok, attach to your next post an archive with sources, pro-file and ui-file.

    Qt Assistant — rocks!
    please, use tags [CODE] & [/CODE].

    ---

15. 16th June 2009, 08:43

    
    

    #15

    Re: Expected class-name before ‘{‘ token
    

    Are we blind or what?

    The class is called Ui::MainWindow, not Ui::MainWindowDLG!

    The line should say:

    class MainWindow : public QMainWindow, private Ui::MainWindow
    To copy to clipboard, switch view to plain text mode 
    

    Your biological and technological distinctiveness will be added to our own. Resistance is futile.

    Please ask Qt related questions on the forum and not using private messages or visitor messages.

    

    ---

16. 16th June 2009, 09:48

    
    

    #16

    Re: Expected class-name before ‘{‘ token
    

    Originally Posted by wysota
    

    Are we blind or what?

    The class is called Ui::MainWindow, not Ui::MainWindowDLG!

    The line should say:

    class MainWindow : public QMainWindow, private Ui::MainWindow
    To copy to clipboard, switch view to plain text mode 
    

    damn, you are right!

    Qt Assistant — rocks!
    please, use tags [CODE] & [/CODE].

    ---

17. 16th June 2009, 11:37

    
    

    #17

    Re: Expected class-name before ‘{‘ token
    

    That’s it! Builds without any problems. Of course when I try to run the program I get an error message and the program doesn’t start. «The application image_2 quit unexpectedly» And I got to ignore, report, or relaunch. I guess the fun is just beginning. Thanks for your help. I got a feeling I’ll be back.

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