To connect principal window with a second one

[ChrisW67]

Stanfillirenfro. You need to look at how you are constructing your Essaie objects. Essaie is a QMainWindow but you are creating a new QMainWindow instance in the constructor. You then create a QPushButton that is parented to the Essaie object and don't use a layout.

As for the specific issue with the m_butonDisplay button, you do not show any code to do with this button or the construction or display of an associated window. It may be a simple problem with the connect() call (you should see a message in your debug window if this is the case) , or somewhere else, we cannot tell.

As an aside, I am a native English speaker with approximately 50 French words in my vocabulary but I don't have too much trouble with code in French unless extensive comments are required to understand what is going on.

[Stanfillirenfro]

I really appreciate your comments and help. Also for the langauge, I am really sorry! I will make sure in the future that english is used.
Concerning my problem, I have revised deeply the code following your recommendations and I have make it clearer. Until now, I can't have any window after compilation. I received the following message: "The program ended abruptly".
I would be greatfull to any of you if you help me solving this problem.

Below is the new code with more modifications:

MainWindow.h:

#ifndef DEF_MAINWINDOW
#define DEF_MAINWINDOW
 
#include <QtGui>
 
class MainWindow: public QMainWindow
{
    Q_OBJECT
 
 
public:
    MainWindow();
    ~MainWindow();
 
protected slots:
    void openFile();
    void saveFile();
    void codage();
    void openChildWindow();
 
private:
    QWidget *m_MainWindow;
    QPushButton *m_Exit;    
    QRadioButton *m_codage;    
    QLineEdit *m_openFile, *m_saveFile;
 
 
};
#endif

#ifndef DEF_MAINWINDOW
#define DEF_MAINWINDOW

#include <QtGui>

class MainWindow: public QMainWindow
{
    Q_OBJECT


public:
    MainWindow();
    ~MainWindow();

protected slots:
    void openFile();
    void saveFile();
    void codage();
    void openChildWindow();

private:
    QWidget *m_MainWindow;
    QPushButton *m_Exit;    
    QRadioButton *m_codage;    
    QLineEdit *m_openFile, *m_saveFile;
    

};
#endif

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ChildWindow.h:

#ifndef DEF_CHILDWINDOW
#define DEF_CHILDWINDOW
 
#include<QtGui>
 
class ChildWindow: public QMainWindow
{
    Q_OBJECT
 
 
public:
    ChildWindow(QWidget *parent);
    ~ChildWindow();
 
 
private:
    QPushButton m_exitChildWindow, *m_seqPur;
 
 
};
#endif // CHILDWINDOW_H

#ifndef DEF_CHILDWINDOW
#define DEF_CHILDWINDOW

#include<QtGui>

class ChildWindow: public QMainWindow
{
    Q_OBJECT


public:
    ChildWindow(QWidget *parent);
    ~ChildWindow();


private:
    QPushButton m_exitChildWindow, *m_seqPur;
    

};
#endif // CHILDWINDOW_H

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MainWindow.cpp:

#include "MainWindow.h"
#include "ChildWindow.h"
 
 
MainWindow::MainWindow()
{
    this->setFixedSize(500, 230);
    m_exit = new QpsuButton("Exit", this);
    m_codage = new QRadioButton(this);
    m_codage->move(50,120);
 
    setCentralWidget(this);
 
 
    connect(m_exit, SIGNAL(triggered()), qApp, SLOT(quit()));
    connect(m_openFile, SIGNAL(clicked()), this, SLOT(openFile()));
    connect(m_saveFile, SIGNAL(clicked()), this, SLOT(saveFile()));
    connect(m_codage, SIGNAL(clicked()), this, SLOT(codage()));
 
}
 
void MainWindow::openFile()
{
    QString file = QFileDialog::getOpenFileName(this, "Information", "Open", "*.text");
    m_openFile->setText(file);
}
 
void MainWindow::saveFile()
{
    QString file = QFileDialog::getSaveFileName(this, "Information", "Save");
    m_saveFile->setText(file);
}
 
 
void MainWindow::codage()
{
 
    QFile file1("myText1.txt");
    QFile file2("myText2.txt);
    QString line;
 
    if(!file1.open(QIODevice::ReadOnly))
    {
        QMessageBox::critical(this, "Warning", "Open a file please");
        return;
    }
 
    file2.open(QIODevice::WriteOnly);
    QTextStream out(&file2);
 
 
      line = line.remove(1, 5);
 
 
        out<< line<<"\r\n\r\n";
}
 
void MainWindow::openChildWindow()
{
    ChildWindow *fene = new ChildWindow(this);
    fene->show();
 
}
 
MainWindow::~MainWindow()

#include "MainWindow.h"
#include "ChildWindow.h"


MainWindow::MainWindow()
{
    this->setFixedSize(500, 230);
    m_exit = new QpsuButton("Exit", this);
    m_codage = new QRadioButton(this);
    m_codage->move(50,120);
    
    setCentralWidget(this);


    connect(m_exit, SIGNAL(triggered()), qApp, SLOT(quit()));
    connect(m_openFile, SIGNAL(clicked()), this, SLOT(openFile()));
    connect(m_saveFile, SIGNAL(clicked()), this, SLOT(saveFile()));
    connect(m_codage, SIGNAL(clicked()), this, SLOT(codage()));

}

void MainWindow::openFile()
{
    QString file = QFileDialog::getOpenFileName(this, "Information", "Open", "*.text");
    m_openFile->setText(file);
}

void MainWindow::saveFile()
{
    QString file = QFileDialog::getSaveFileName(this, "Information", "Save");
    m_saveFile->setText(file);
}


void MainWindow::codage()
{

    QFile file1("myText1.txt");
    QFile file2("myText2.txt);
    QString line;

    if(!file1.open(QIODevice::ReadOnly))
    {
        QMessageBox::critical(this, "Warning", "Open a file please");
        return;
    }

    file2.open(QIODevice::WriteOnly);
    QTextStream out(&file2);

                
      line = line.remove(1, 5);
        
        
        out<< line<<"\r\n\r\n";
}

void MainWindow::openChildWindow()
{
    ChildWindow *fene = new ChildWindow(this);
    fene->show();

}

MainWindow::~MainWindow()

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ChildWindow.cpp:

#include "Fenetre1.h"
 
ChildWindow::ChildWindow(QWidget *parent = 0): QMainWindow(parent)
{
 
       m_exitChildWindow = new QPushButton("Exit", this);
       m_exitChildWindow->move(200, 220);
 
       m_seqPur = new QPushButton;
       m_seqPur->move(175, 220);
 
       resize(475, 250);
 
 
       connect(m_seqPur, SIGNAL(clicked()), this , SLOT(openChildWindow()));
       connect(m_exitChildWindow, SIGNAL(clicked()), this, SLOT(close()));
 
 
}
 
ChildWindow::~ChildWindow()
{}

#include "Fenetre1.h"

ChildWindow::ChildWindow(QWidget *parent = 0): QMainWindow(parent)
{

       m_exitChildWindow = new QPushButton("Exit", this);
       m_exitChildWindow->move(200, 220);

       m_seqPur = new QPushButton;
       m_seqPur->move(175, 220);

       resize(475, 250);


       connect(m_seqPur, SIGNAL(clicked()), this , SLOT(openChildWindow()));
       connect(m_exitChildWindow, SIGNAL(clicked()), this, SLOT(close()));


}

ChildWindow::~ChildWindow()
{}

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Main.cpp:

#include <QApplication>
#include "MainWindow.h"
 
 
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
 
    MainWindow fenPr;
 
    fenPr.show();
 
    return app.exec();
}

#include <QApplication>
#include "MainWindow.h"


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

    MainWindow fenPr;

    fenPr.show();

    return app.exec();
}

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Many thanks in advance!

[ChrisW67]

Did you copy and paste that code from a building program? It won't build as is.

ChildWindow does not have a slot called openChildWindow(), so clicking on the m_seqPur button will not do anything.

Please read Layout Management before you try to build anything more complicated. You will save yourself a lot of work and frustration.

[Stanfillirenfro]

ChrisW67, many thanks for your comments. I realise now that I had some errors in my code. The code was just part of a big one I am implementing now. I could not sent it all, otherwise it would be too big and could discourage the readers.
Anyway, based on your many comments, I could overcome partially the problem. Now, I can compile the code in DEBUG mode, but not in relaese one. In release mode, when I have the macro Q_OBJECT in header's child file, such reply from the program is sent out: "undefined reference to `vtable for Childwindow" and the compilation fails. When I remove the macro Q_OBJECT, I have acces to all windows, but the slots on the Childwindow do not work.
Could you please give me some advises to overcome this barrier?
Many thanks in advance.

[Spitfire]

When you add the Q_OBJECT macro to a class you have to re-run qmake.
To be on the safe side just clear the whole project and build it again.
This should fix the vtable error.

[Stanfillirenfro]

Many thanks Spitfire and also to all of you for your help. By clearing the whole project and rebuilding it new, it compile now properly. The problems are solved.
Many thanks one more time.