Signal and Slot

[juraj]

Hi i am new in Qt and i try to join signal "clicked" from QPushbutton with my own slot "Slot" but it is not working, and i dont know what i doing wrong
could you help me?

window.h

#ifndef Window_H
#define Window_H
 
#include <QWidget>
 
class Window : public QWidget
{
    Q_OBJECT
public:
    explicit Window(QWidget *parent=0);
    ~Window();
};
#endif

#ifndef Window_H
#define Window_H

#include <QWidget>

class Window : public QWidget
{
    Q_OBJECT
public:
    explicit Window(QWidget *parent=0);
    ~Window();
};
#endif

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value.h

#ifndef VALUE_H
#define VALUE_H
#include <QObject>
 
class Value : public QObject
{
    Q_OBJECT
public:
    explicit Value(QObject *parent=0);
    ~Value();
public:
    void Fu_1(){cx=76;}
    int Fu_2(){return cx;}
public slots:
    void Slot();
private:
    int cx;
};
 
#endif // VALUE_H

#ifndef VALUE_H
#define VALUE_H
#include <QObject>

class Value : public QObject
{
    Q_OBJECT
public:
    explicit Value(QObject *parent=0);
    ~Value();
public:
    void Fu_1(){cx=76;}
    int Fu_2(){return cx;}
public slots:
    void Slot();
private:
    int cx;
};

#endif // VALUE_H

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window.cpp

#include "window.h"
 
Window::Window(QWidget *parent):QWidget(parent)
{
}
 
Window::~Window()
{
}

#include "window.h"

Window::Window(QWidget *parent):QWidget(parent)
{
}

Window::~Window()
{
}

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value.cpp

#include "value.h"
 
Value::Value(QObject *parent):QObject(parent)
{
}
 
Value::~Value()
{
}
 
void Value::Slot()
{
    Fu_1();
}

#include "value.h"

Value::Value(QObject *parent):QObject(parent)
{
}

Value::~Value()
{
}

void Value::Slot()
{
    Fu_1();
}

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main.cpp

#include <QApplication>
#include "window.h"
#include "value.h"
#include <QtWidgets>
#include <QHBoxLayout>
 
 
int main(int argc, char*argv[])
{
    QApplication app(argc,argv);
    Window *Win=new Window;
    QPushButton *Object_1=new QPushButton;
    QLCDNumber *Object_2=new QLCDNumber;
    Value *Object_3=new Value;
    QHBoxLayout *Lay=new QHBoxLayout;
 
    QObject::connect(Object_1,SIGNAL(clicked()),Object_3,SLOT(Slot()));   // this is not working
    Object_3->Fu_1();  // but when i try to call Fu_1 through Object its working normaly
    int x;
    x=Object_3->Fu_2();
    Object_2->display(x); // it is working because value of cx was set on 76
 
    Lay->addWidget(Object_1);
    Lay->addWidget(Object_2);
 
    Win->setLayout(Lay);
    Win->show();
    return app.exec();
}

#include <QApplication>
#include "window.h"
#include "value.h"
#include <QtWidgets>
#include <QHBoxLayout>


int main(int argc, char*argv[])
{
    QApplication app(argc,argv);
    Window *Win=new Window;
    QPushButton *Object_1=new QPushButton;
    QLCDNumber *Object_2=new QLCDNumber;
    Value *Object_3=new Value;
    QHBoxLayout *Lay=new QHBoxLayout;

    QObject::connect(Object_1,SIGNAL(clicked()),Object_3,SLOT(Slot()));   // this is not working
    Object_3->Fu_1();  // but when i try to call Fu_1 through Object its working normaly
    int x;
    x=Object_3->Fu_2();
    Object_2->display(x); // it is working because value of cx was set on 76

    Lay->addWidget(Object_1);
    Lay->addWidget(Object_2);

    Win->setLayout(Lay);
    Win->show();
    return app.exec();
}

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[hayzel]

Win->show() is equivalent of setVisible(true). It shows up the QWindow.
To start its events, you have to add after showing-up the window:

Win->activateWindow();

Win->activateWindow();

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[wysota]

Win->show() is equivalent of setVisible(true). It shows up the QWindow.
To start its events, you have to add after showing-up the window:

Win->activateWindow();

Win->activateWindow();

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No, that's not true, you don't have to do anything like that.

[ChrisW67]

QObject::connect(Object_1,SIGNAL(clicked()),Object _3,SLOT(Slot())); // this is not working

QObject::connect(Object_1,SIGNAL(clicked()),Object _3,SLOT(Slot())); // this is not working

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How do you determine this? The slot is not called until the button is clicked, when the program is in app.exec(), and does not do anything that is outwardly visible.