invalid use of this in non member function

[dineshkumar]

hi i want to do a qt mobile apps which using network access but while compiling my code it shows the following errors.

i. invalid use of this in non member function
ii. connect was not declared in this scope

I have do the following in my code:

.pro file:

QT       += network

QT       += network

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main.cpp file

#include <QtGui/QApplication>
#include "mainwindow.h"
#include <QtNetwork>
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
 
    QNetworkAccessManager *manager = new QNetworkAccessManager(this);
    connect(manager, SIGNAL(finished(QNetworkReply*)),
            this, SLOT(replyFinished(QNetworkReply*)));
 
    manager->get(QNetworkRequest(QUrl("http://qt.nokia.com")));
 
#if defined(Q_WS_S60)
    w.showMaximized();
#else
    w.show();
#endif
    return a.exec();
}

#include <QtGui/QApplication>
#include "mainwindow.h"
#include <QtNetwork>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;

    QNetworkAccessManager *manager = new QNetworkAccessManager(this);
    connect(manager, SIGNAL(finished(QNetworkReply*)),
            this, SLOT(replyFinished(QNetworkReply*)));

    manager->get(QNetworkRequest(QUrl("http://qt.nokia.com")));

#if defined(Q_WS_S60)
    w.showMaximized();
#else
    w.show();
#endif
    return a.exec();
}

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Is it any problem with my code please help me. Thanks.

[wysota]

connect() is a method of QObject and not a standalone function.

QObject::connect(manager, SIGNAL(finished(QNetworkReply*)),
                     this, SLOT(replyFinished(QNetworkReply*)));

QObject::connect(manager, SIGNAL(finished(QNetworkReply*)),
                     this, SLOT(replyFinished(QNetworkReply*)));

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[dineshkumar]

hi thanks,
But it again shows the following error:

invalid use of this in non member function

[wysota]

There is no "this" in main().

[nish]

replyFinished(QNetworkReply*)

replyFinished(QNetworkReply*)

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where is this function defined? you need that class object to be passed in connect instead of "this", the same as you pass "manager".

[helloworld]

It is probably easier if you move your code to the MainWindow instead:

main.cpp:

// main.cpp
 
#include <QtGui/QApplication>
#include "mainwindow.h"
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
 
#if defined(Q_WS_S60)
    w.showMaximized();
#else
    w.show();
#endif
 
    return a.exec();
}

// main.cpp

#include <QtGui/QApplication>
#include "mainwindow.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;

#if defined(Q_WS_S60)
    w.showMaximized();
#else
    w.show();
#endif

    return a.exec();
}

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mainwindow.h:

// mainwindow.h
 
#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <QtGui/QMainWindow>
 
class QNetworkReply;
 
class MainWindow : public QMainWindow
{
    Q_OBJECT
 
public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
 
protected slots:
    void replyFinished(QNetworkReply *reply);
};
 
#endif // MAINWINDOW_H

// mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QtGui/QMainWindow>

class QNetworkReply;

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

protected slots:
    void replyFinished(QNetworkReply *reply);
};

#endif // MAINWINDOW_H

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mainwindow.cpp

// mainwindow.cpp
 
#include <QtNetwork/QtNetwork>
#include <QtNetwork/QNetworkReply>
#include "mainwindow.h"
#include <QDebug>
 
MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent)
{
    QNetworkAccessManager *manager = new QNetworkAccessManager(this);
    connect(manager, SIGNAL(finished(QNetworkReply*)),
               this, SLOT(replyFinished(QNetworkReply*)));
 
    manager->get(QNetworkRequest(QUrl("http://qt.nokia.com")));
}
 
MainWindow::~MainWindow()
{
}
 
void MainWindow::replyFinished(QNetworkReply *reply)
{
    qDebug() << "ok!";
}

// mainwindow.cpp

#include <QtNetwork/QtNetwork>
#include <QtNetwork/QNetworkReply>
#include "mainwindow.h"
#include <QDebug>

MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent)
{
    QNetworkAccessManager *manager = new QNetworkAccessManager(this);
    connect(manager, SIGNAL(finished(QNetworkReply*)),
               this, SLOT(replyFinished(QNetworkReply*)));

    manager->get(QNetworkRequest(QUrl("http://qt.nokia.com")));
}

MainWindow::~MainWindow()
{
}

void MainWindow::replyFinished(QNetworkReply *reply)
{
    qDebug() << "ok!";
}

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[dineshkumar]

Thankyou friend its works..

[tylor2000]

Thank you helloworld, this helped me out a lot. You will probably never see this but just wanted to thank you for the code example. It's still helping people out after all these years.