Retrieve information from mainwindow and display the information on newwindow::issues

QT_QT_QT

Greetings,

Regarding to the title above, i m trying to use SIGNAL and SLOT method for implementation . Here my codes:

***mainwindow.h****

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QObject>
#include <QString>
#include "newwindow.h"

class mainWindow
{
    int i_value;
    newWindow *myNewWindow();


public:
    mainWindow();
    void setI_Value(int x);
    int getI_Value();
    void changeValueTo(int y);


signals:
    void dataAvailable(const int &y);


};

#endif // MAINWINDOW_H

***newwindow.h***

#ifndef NEWWINDOW_H
#define NEWWINDOW_H

#include <QObject>

class newWindow
{
public:
    newWindow();
slots:
    void getDataFromMainWindow(int &y);
};

#endif // NEWWINDOW_H

***mainwindow.cpp***

#include "mainwindow.h"
#include "newwindow.h"
#include <QObject>

using namespace std;

mainWindow::mainWindow()
{
    i_value = 10;
    QObject::connect(this,SIGNAL(dataAvailable(int)),myNewWindow,SLOT(getDataFromMainWindow(int)));

}
void mainWindow::setI_Value(int x)
{
   i_value = x;
}

int mainWindow::getI_Value()
{
    return i_value;
}

void mainWindow::changeValueTo(int &y)
{
    if (y!=i_value){
        i_value = y;
        emit dataAvailable(y);

   }
}

***newwindow.cpp***

#include "newwindow.h"
#include "mainwindow.h"
#include <QObject>


newWindow::newWindow()
{

}

void newWindow::getDataFromMainWindow(int y)
{
    int xyz = z;
    qDebug()<< xyz;
}

Do spend some time to understand the codes, its quite simple to understand . Hoping you will get the full picture after you gain the understanding from my code. Now, when i compile them , i get a lot of error which me also dont understanding what is happening . Someone here please share with me your knowledge on this approach. Spend so many days to solve this issue. Without solving this issue, i can not proceed to my next task!Thank you in advance!

Andy314

Whats that: newWindow *myNewWindow(); ?

I cannot understand your code. Mainwindow has not a base class. Is is not really a window !?

You can use signals and slots only in subclasses of a QObject and you must use the Q_OBJECT macro.

class SubClass : public QObject
{ Q_OBJECT
signals:
slots:
}

QT_QT_QT

@Andy314

Hi ,

The thing that you asked is to create a new object from NewWidow, an object from created different class. The purpose of this is i want to "put" this object in the connect function . something like this :

QObject :: connect (this, SIGNAL(dataAvailable(int y)),myNewWindow,SLOT(getDataFromMainWindow(int y)));

the signal is emitted from main window , and the search for the slots in new Window .

jsulm

Please read http://doc.qt.io/qt-5.6/signalsandslots.html
As @Andy314 already said the class newWindow must be a subclass of QObject and have Q_OBJECT macro in it in order to use signals/slots!