change progress bar value from a thread

hi every one.
i write this cod.
how i can change progress bar value from my thread?
signal and slots?
how use signal and slots for this program??


main.cpp

Code:

---

#include "mainwindow.h"
#include <QApplication>
#include <QThread>
#include <QDebug>
#include <mainwindow.h>
 
 
 
 
int i ;
 
 
 
 
 
 
 
 
 
 
 
 
 
class Thread : public QThread
{
private:
    void run()
    {
    for(i;i<=100;i++)
        QThread::sleep(1);
 
    }
 
};
 
 
 
 
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
 
 
 
//Thread();
 
 
 
 
 
      qDebug()<<"From main thread: "<<QThread::currentThreadId();
 
       Thread t;
       QObject::connect(&t, SIGNAL(finished()), &a, SLOT(quit()));
 
       t.start();
 
 
//--------------------
 
 
//---------------------------------------
 
 
 
 
 
 
 
 
    return a.exec();
 
}

---

mainwindow.cpp:

Code:

---

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QApplication>
 
 
 
 
 
extern int i;
 
 
 
 
 
 
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
 
 
}
 
MainWindow::~MainWindow()
{
    delete ui;
 
}
 
void MainWindow::on_pushButton_pressed()
{
 
   // ui->progressBar->setValue(i);
 
 
//ui->progressBar->update();
 
}

---

Yes, you can add a signal to your thread class and emit it whenever the thread needs to send new progress info.
Connect that to a slot in your main window.

Cheers,
_

Thnak you cheers:). but how i write a connection for this program?
please give me a simple cod

The Qt documentation will teach you all about signals, slots, and connections.

Thank you m freinds. im in learning to write connection. i can write simple connection but for this program i thik much time and nothing come to my mind.
please give me a simple connect for this program:confused:

Try this to start:

Code:

---

// main.cpp
 
#include "mainwindow.h"
#include <QApplication>
#include <QThread>
#include <QDebug>
#include <mainwindow.h>
 
class Thread : public QThread
{
	Q_OBJECT
 
signals:
	void progress( int value );
 
private:
    void run()
    {
		for(int i = 0; i <= 100; i++ )
		{
			emit progress( i );
			QThread::sleep(1);
		}
    }
};
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
 
    qDebug()<<"From main thread: "<<QThread::currentThreadId();
 
	Thread t;
	QObject::connect(&t, SIGNAL(finished()), &a, SLOT(quit()));
	QObject::connect(&t, SIGNAL(progress(int)), &w, SLOT(onProgress(int)));
 
	t.start();
    return a.exec();
}
 
// mainwindow.h
 
class MainWindow : public QMainWindow
{
	Q_OBJECT
 
public:
	MainWindow( QWidget * parent );
	~MainWindow();
 
public slots:
	void onProgress( int i );
 
	// ...
};
 
// mainwindow.cpp
 
#include "mainwindow.h"
#include "ui_mainwindow.h"
 
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}
 
MainWindow::~MainWindow()
{
    delete ui;
}
 
void MainWindow::onProgress( int i )
{
	ui->progressBar->setValue(i);
}

---