Help me

Qt fa schifo

Hi everyone,
I'm learning to use Qt but with a lot of difficulty. I created a TCP network connection but it doesn't work and I can't fix the code. Would some good soul help me?

mytcpsocket.h

#include <QtNetwork/QTcpSocket>
#include <QtNetwork/QAbstractSocket>
#include <QDebug>

QT_BEGIN_NAMESPACE
namespace Ui {
class MyTcpSocket;
}
QT_END_NAMESPACE

class MyTcpSocket : public QMainWindow
{
    Q_OBJECT

public:
    MyTcpSocket(QWidget *parent = nullptr);
    ~MyTcpSocket();
    //    void doConnect();

private slots:
    void on_cmdinvia_clicked();

    void on_cmdconnetti_clicked();

public slots:
    void doConnect();
    void connected();
    void disconnected();
    void bytesWritten(qint64 bytes);
    void readyRead();
   // void subinviadato();
    void subinviadatotest();

private:
    Ui::MyTcpSocket *ui;
        QTcpSocket *socket;


};
#endif // MYTCPSOCKET_H

main.cpp

#include "mytcpsocket.h"

#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MyTcpSocket w;
    w.show();
    return a.exec();
}

mytcpsocket.cpp

#include "mytcpsocket.h"
#include "ui_mytcpsocket.h"
#include "QTimer"
#include <QThread>
#include <QString>
#include <QObject>
#include <QtNetwork/QTcpSocket>
#include <QtNetwork/QAbstractSocket>
#include <QDebug>
#include <QtWidgets>

MyTcpSocket::MyTcpSocket(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MyTcpSocket)
{
    ui->setupUi(this);
}

MyTcpSocket::~MyTcpSocket()
{
    delete ui;
}

void MyTcpSocket::on_cmdinvia_clicked()
{
    subinviadatotest();
}


void MyTcpSocket::on_cmdconnetti_clicked()
{
    readyRead();
    doConnect();
}

//void subinviadato();


//MyTcpSocket::MyTcpSocket(QObject *parent) :
//    QObject(parent)
//{
//}


void MyTcpSocket::doConnect()
{
    //socket = new QTcpSocket(this); //NON FUNZIONA
    //QTcpSocket socket;

    connect(socket, SIGNAL(connected()),this, SLOT(connected()));
    connect(socket, SIGNAL(disconnected()),this, SLOT(disconnected()));
    //connect(socket, SIGNAL(bytesWritten(1)),this, SLOT(bytesWritten(1)));
    connect(socket, SIGNAL(readyRead()),this, SLOT(readyRead()));

    qDebug() << "connecting...";

    // this is not blocking call
    socket->connectToHost("192.168.1.26", 88);

    // we need to wait...
    if(!socket->waitForConnected(5000))
    {
        qDebug() << "Error: " << socket->errorString();
    }
}

void MyTcpSocket::connected()
{
    qDebug() << "connected...";

     subinviadatotest();

}

void MyTcpSocket::subinviadatotest()
{
    //Dichiaro variabili che uso;
    QChar str;
    QString stringa;
    stringa = "{P01-P07-DAT-AXX}";
    long lunghezza;

    // (const char *)&str << stringa.at(stringa.length() - 2);
    //qDebug() str;

    //Misuro lunghezza stringhe
    lunghezza=stringa.length();

    //Visualizzo informazioni
    qDebug("  ---  ");
    QString ss = QString::number(lunghezza);
    qDebug() << ss;
    qDebug("  ---  ");

    long i;
    for(i=0;i<lunghezza;i++) {

        //if(stringa[i]=='}')
        //    break;
        QChar caratt;
        caratt=stringa[i];
        //qDebug("-");
        //qDebug() << caratt;
        str= caratt; //QChar('{');
        //const char *str = qPrintable(stringa);

        socket->write((const char *)&str, 1);
        socket->waitForBytesWritten(1000);
        QThread::msleep(100);

    }


}



void MyTcpSocket::disconnected()
{
    qDebug() << "disconnected...";
}

void MyTcpSocket::bytesWritten(qint64 bytes)
{
    qDebug() << bytes << " bytes written...";
}

void MyTcpSocket::readyRead()
{
    qDebug() << "reading...";

    // read the data from the socket
    qDebug() << socket->readAll();
}

mytcpsocket.ui

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MyTcpSocket</class>
 <widget class="QMainWindow" name="MyTcpSocket">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>800</width>
    <height>600</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MyTcpSocket</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <widget class="QPushButton" name="cmdinvia">
    <property name="geometry">
     <rect>
      <x>600</x>
      <y>490</y>
      <width>181</width>
      <height>29</height>
     </rect>
    </property>
    <property name="text">
     <string>Invia</string>
    </property>
   </widget>
   <widget class="QLineEdit" name="txtinvia">
    <property name="geometry">
     <rect>
      <x>30</x>
      <y>490</y>
      <width>561</width>
      <height>26</height>
     </rect>
    </property>
   </widget>
   <widget class="QTextEdit" name="txtricevuto">
    <property name="geometry">
     <rect>
      <x>30</x>
      <y>60</y>
      <width>751</width>
      <height>421</height>
     </rect>
    </property>
   </widget>
   <widget class="QPushButton" name="cmdconnetti">
    <property name="geometry">
     <rect>
      <x>520</x>
      <y>10</y>
      <width>231</width>
      <height>41</height>
     </rect>
    </property>
    <property name="text">
     <string>Connetti</string>
    </property>
   </widget>
  </widget>
  <widget class="QMenuBar" name="menubar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>800</width>
     <height>26</height>
    </rect>
   </property>
  </widget>
  <widget class="QStatusBar" name="statusbar"/>
 </widget>
 <resources/>
 <connections/>
</ui>

I use Qt 12.0.2 with 6.6.2 min gw

Ronel_qtmaster

@Qt-fa-schifo hi and welcome to qt forum.As You are a beginner, i would advice you to check this https://www.bogotobogo.com/Qt/Qt5_QTcpSocket_Signals_Slots.php

SGaist

Hi and welcome to devnet,

Beside the recommendation of @Ronel_qtmaster, you commented out the line where you create the QTcpSocket object so it can't even start to work.

JonB

@Qt-fa-schifo
The first thing is to define/explain to us what "but it doesn't work" means exactly.

What was the problem with

//socket = new QTcpSocket(this); //NON FUNZIONA

How did it "not work"? As @SGaist says that is needed to create the socket.

And I suspect you are working from https://www.bogotobogo.com/Qt/Qt5_QTcpSocket_Signals_Slots.php. It helps if you say so.

There is another Qt example at https://doc.qt.io/qt-6/qtnetwork-fortuneclient-example.html, just so you know. However for now you probably want to stick with one you have started on.

Qt fa schifo

what I can't understand is why if I activate socket = new QTcpSocket(this); the program gives me the following error:

:-1: error: debug/mytcpsocket.o: in function MyTcpSocket::doConnect()': C:........\Qt\esempio3\untitled\mytcpsocket.cpp:47: error: undefined reference to __imp__ZN10QTcpSocketC1EP7QObject'
:-1: error: collect2.exe: error: ld returned 1 exit status
:-1: warning: The build directory is not at the same level as the source directory, which could be the reason for the build failure.
:-1: error: [Makefile.Debug:72: debug/untitled.exe] Error 1

while if I leave it deactivated the program starts and then crashes.

it should be the other way around, I don't understand....

Ronel_qtmaster

@Qt-fa-schifo following your code, it seems you don't even understand to basic syntax
here:
socket = new QTcpSocket(this); //NON FUNZIONA
QTcpSocket socket;
you are creating two different sockets with the same name.
please when begining you should follow official exemples.Simply follow the link i sent you

Qt fa schifo

that was a comment from another example and it was disabled so it doesn't cause the program to not work.
If I create a new project and paste the bogotobogo examples into it they don't work.
version incompatibility?

JonB

@Qt-fa-schifo
If you do not have line socket = new QTcpSocket(this); then socket will be uninitialized and your program would be expected to crash.

You do need socket = new QTcpSocket(this); . The error you show is a linker error. You are either not linking with the right libraries, or possibly the wrong version.

I see you are MinGW, are you using qmake or cmake?

Qt fa schifo

I'm using qmake.

in effect with the original libraries

#include <QTcpSocket>
#include <QAbstractSocket>

give me error (file not found), I thought maybe are moved:

#include <QtNetwork/QTcpSocket>
#include <QtNetwork/QAbstractSocket>

so could this is the problem?
How do I find the right QTcpSocket and QAbstractSocket?

Qt fa schifo

I changed compiler but the error is still the same...

ChrisW67

@Qt-fa-schifo In your PRO file do you have:

QT += network

See Qt Network

Helmut.Jakoby

Hello my dear @Qt-is-shit (translation by @Qt-fa-schifo from Italian).
If so, why are you using Qt? And do you think you can get better answers with this nickname?

Qt fa schifo

@ChrisW67 thank you very very very very very very very very very much

JonB

@Qt-fa-schifo
Just so you know: if you had showed your .pro from the start or said you were using qmake we could have guessed you were missing QT += network, that is why I asked whether you were qmake or cmake.