connect signal to slot crazy problem

[fireghostea]

this is my main.cpp

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QTcpSocket>
#include <QTcpServer>
#include "handler.h"

handler *h = new handler();
int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
    QGuiApplication app(argc, argv);

    QQmlApplicationEngine engine;
    engine.load(QUrl(QLatin1String("qrc:/main.qml")));
    return app.exec();
}

this is my handler.h

#ifndef HANDLER_H
#define HANDLER_H

#include <QObject>
#include <QTcpServer>
#include <QTcpSocket>
class handler : public QObject
{
    Q_OBJECT
public:
    explicit handler(QObject *parent = 0);

signals:
 void mysignal();
public slots:
    void newConnection();
private:
    QTcpServer *mserver;
    QTcpSocket* socket;
};

#endif // HANDLER_H

this is my handler.cpp

#include "handler.h"

handler::handler(QObject *parent) : QObject(parent)
{
    mserver =  new QTcpServer();
    connect(
         mserver, &QTcpServer::newConnection,
         this , &handler::newConnection
    );
    if(!mserver->listen(QHostAddress::Any, 1234)){
            qDebug() << "connection failed";
    }else{
            qDebug() << "connection success!!";
    }

}


void handler::newConnection(){
    qDebug() << "connection Accepted";
    QTcpSocket* socket = mserver->nextPendingConnection();
    socket->write("HELLO WORLD!\r\n");
    socket->waitForBytesWritten(300);
    socket->close();
}

this code should should should be work but does not work why?
newConnection slot does not fire

[jsulm]

@fireghostea Where exactly did you put this line now? It must be after QGuiApplication app(argc, argv);

[Asperamanca]

@fireghostea said in connect signal to slot crazy problem:

handler *h = new handler();

The position of this code line outside of any method does not make much sense to me.

[fireghostea]

@Asperamanca i change the position to in the main function and the problem does not solve

[jsulm]

@fireghostea Where exactly did you put this line now? It must be after QGuiApplication app(argc, argv);

[fireghostea]

@jsulm yeeeeees you solve it tnx

[yuvaram]

HI @fireghostea

Before initializing any Qt object, "QApplication app(argc, argv);" should be initialized. Because it initializes all the QObject , Meta object related objects.
Without initializing QApplication if signal & slots connected, there is no use.

The same case with your case , where " handler *h = new handler(); " is initialized before QApplication.