c++ - Qt - Simple example using threads controlled by push buttons -

i have been trying simple example using threads activated pushbuttons work. based off of solution in question below:

how implement frequent start/stop of thread (qthread)

the main differences between example solution above , code below are:

1. i used qwidget instead of mainwindow
2. i changed name of signals clarity
3. my code contains debugging information
4. i experimented eliminating signals created worker didn't appear anything

it appears start/stop signals not triggering corresponding slots, not experienced enough troubleshoot why.

additionally, unsure of purpose of signal:

signaltoobj_mainthreadgui()

is used , not?

i have been trying code work time, appreciated.

main.cpp

#include "threadtest.h" #include <qapplication>  int main(int argc, char *argv[])  {     qapplication a(argc, argv);     threadtest w;     w.show();      return a.exec();  } 

threadtest.h

#include <qwidget> #include <qthread> #include "worker.h"       namespace ui  {     class threadtest; }  class threadtest : public qwidget {     q_object  public:     explicit threadtest(qwidget *parent = 0);     ~threadtest();  signals:     void startworksignal();     void stopworksignal();   private slots:     void on_startbutton_clicked();     void on_stopbutton_clicked();  private:     ui::threadtest *ui;     worker *myworker;     qthread *workerthread; }; 

threadtest.cpp

#include "threadtest.h" #include "ui_threadtest.h"  threadtest::threadtest(qwidget *parent) : qwidget(parent), ui(new ui::threadtest)  {     ui->setupui(this);      myworker = new worker;     workerthread = new qthread;     myworker->movetothread(workerthread);      connect(this,             signal(startworksignal()),             myworker,             slot(startwork())             );      connect(this,             signal(stopworksignal()),             myworker,             slot(stopwork())             );      //debug     this->dumpobjectinfo();     myworker->dumpobjectinfo();  }  threadtest::~threadtest()  {     delete ui;  }  void threadtest::on_startbutton_clicked()  {     qdebug() << "startwork signal emmitted";     emit startworksignal();  }  void threadtest::on_stopbutton_clicked()  {     qdebug() << "stopwork signal emmitted";     emit stopworksignal();  } 

worker.h

#include <qobject> #include <qdebug>  class worker : public qobject {     q_object  public:     explicit worker(qobject *parent = 0);     ~worker();  signals:     void signaltoobj_mainthreadgui();     //void running();     //void stopped();  public slots:     void stopwork();     void startwork();  private slots:     void do_work();  private:     volatile bool running, stopped;  }; 

worker.cpp

#include "worker.h"  worker::worker(qobject *parent) : qobject(parent), stopped(false), running(false)  {     qdebug() << "running: " << running;     qdebug() << "stopped: " << stopped;   }   worker::~worker() {}  void worker::do_work()  {     qdebug() << "inside work";     emit signaltoobj_mainthreadgui();      if (!running || stopped) return;      // actual work here     /*     (int = 0; < 100; i++)     {         qdebug() << "count: " + i;     }     */     qmetaobject::invokemethod(this, "do_work", qt::queuedconnection);  }  void worker::stopwork()  {     qdebug() << "inside stopwork";     stopped = true;     running = false;      //emit stopped();  }  void worker::startwork()  {     qdebug() << "inside startwork";     stopped = false;     running = true;      //emit running();     do_work();  } 

you should write

workerthread->start(); 

or can use thread of threadtest object instead workerthread (in case workerthread needless):

 myworker->movetothread(thread()); // this->thread