How to run a timer inside a QThread?

Question

I would like to run a timer inside a QThread. I have written some code in which i am getting some error during the run time. Please guide me into the right direction. What a

Answer 1

In order to do this, you need to have event loop in your thread.

From QTimer's man page:

In multithreaded applications, you can use QTimer in any thread that has an event loop. To start an event loop from a non-GUI thread, use QThread::exec(). Qt uses the timer's thread affinity to determine which thread will emit the timeout() signal. Because of this, you must start and stop the timer in its thread; it is not possible to start a timer from another thread.

From QThread's man page:

int QThread::exec () [protected]

Enters the event loop and waits until exit() is called, returning the value that was passed to exit(). The value returned is 0 if exit() is called via quit(). It is necessary to call this function to start event handling.

Also, you need to have Q_OBJECT in your class:

class MyThread:public QThread
{
    Q_OBJECT

And finally, as Dmitry noted, you need to create QTimer inside your thread, so the entire cpp file should look like this:

#include "mythread.h"

MyThread::MyThread()
{       
}

void MyThread::run()
{
    thr= new QTimer();
    connect(thr,SIGNAL(timeout()),this,SLOT(slo()));
    thr->start(1000);
    exec();
}

void MyThread::slo()
{
    int i = 0,j=0;
    i=i+j;
}

Also, read this document.