Qt Forum

    • Login
    • Search
    • Categories
    • Recent
    • Tags
    • Popular
    • Users
    • Groups
    • Search
    • Unsolved

    [SOLVED]Cann't create signals ?

    Installation and Deployment
    2
    5
    817
    Loading More Posts
    • Oldest to Newest
    • Newest to Oldest
    • Most Votes
    Reply
    • Reply as topic
    Log in to reply
    This topic has been deleted. Only users with topic management privileges can see it.
    • D
      DiIvPa last edited by

      Dear Qt Forumers, I wrote simple programm to learn more about threads ssynchronization and have encountered problem when tried to build executable. The compiler couldn't find reference to one of signals SetMyText(QString, int). Could you please be so kind to help me with this bug (I waste enough time and exhausted). Thank you for help in advance. Please, take a look on codes:
      main.cpp
      @
      #include <QApplication>
      #include "ThreadAB.h"
      #include "MyThread.h"
      #include "MyString.h"
      int main(int argc, char *argv[]){

      QApplication a(argc, argv);
      //    QDebugStream cerr(std::cerr);
      //    QDebugStream cout(std::cout);
      
      ThreadAB *window = new  ThreadAB();
      window -> show();
      
      return a.exec&#40;&#41;;
      

      }
      @

      MyThread.h

      @
      #ifndef MYTHREAD_H
      #define MYTHREAD_H
      #include <QApplication>
      #include <QThread>
      class Thread : public QThread
      {
      public:
      Thread();

      void run();
      void stop();
      void setThreadName(QString);
      QString thread_name;
      int running_number;

      private:
      volatile bool stopped;

      signals:
      void SetMyText (QString, int);
      };
      #endif //MYTHREAD_H
      @

      MyThread.cpp

      @
      #include "MyThread.h"
      #include <QDebug>
      Thread::Thread()
      {
      stopped = false;
      }
      void Thread::run()
      {
      while (!stopped) {
      running_number += 1;
      if(thread_name.left(1) == "A")
      qDebug() << thread_name << ": running_number= " << running_number << endl;
      else
      qDebug() << " "
      << thread_name << ": running_number= " << running_number << endl;

        sleep(1);
      

      }
      emit SetMyText(thread_name, running_number);
      // stopped = false;
      }
      void Thread::stop()
      {
      stopped = true;
      }
      void Thread::setThreadName(QString message)
      {
      thread_name = message;
      running_number = 0;
      }
      @

      ThreadAB.h

      @
      #ifndef THREADAB_H
      #define THREADAB_H
      #include "MyThread.h"
      #include "QDialog"
      #include <QCloseEvent>
      class ThreadAB : public QDialog
      {
      Q_OBJECT

      public: 
      

      ThreadAB(QWidget *parent = 0);

      protected:
      void closeEvent(QCloseEvent *event);

      private:
      Thread *threadA;
      Thread *threadB;
      QPushButton *threadAButton;
      QPushButton *threadBButton;
      QPushButton *quitButton;

      private slots:
      void startOrStopThreadA();
      void startOrStopThreadB();

      };
      #endif //THREADAB_H
      @

      ThreadAB.cpp

      @
      #include "ThreadAB.h"
      #include "MyString.h"
      #include <QTextCodec>
      #include <QPushButton>
      #include <QHBoxLayout>
      ThreadAB::ThreadAB(QWidget *parent)
      : QDialog(parent)
      {
      QTextCodec *utfcodec = QTextCodec::codecForName("UTF-8");
      QTextCodec::setCodecForTr(utfcodec);
      QTextCodec::setCodecForCStrings(utfcodec);

      this->setWindowTitle("Threads");
      threadA = new Thread();
      threadB = new Thread();

      threadA -> setThreadName("A thread");
      threadB -> setThreadName("B thread");
      // threadA -> running_number=0;
      // threadB -> running_number=0;
      threadAButton = new QPushButton(tr("Start A"), this);
      threadBButton = new QPushButton(tr("Start B"), this);
      quitButton = new QPushButton(tr("Quit"), this);
      quitButton -> setDefault(true);
      // layout : start
      QHBoxLayout *layout = new QHBoxLayout;
      layout -> addWidget(threadAButton);
      layout -> addWidget(threadBButton);
      layout -> addWidget(quitButton);
      this -> setLayout(layout);

      connect(threadAButton, SIGNAL(clicked()),
      this, SLOT(startOrStopThreadA()));
      connect(threadBButton, SIGNAL(clicked()),
      this, SLOT(startOrStopThreadB()));
      connect(quitButton, SIGNAL(clicked()),
      this, SLOT(close()));

      MyString *p_str =new MyString();

      QObject::connect(
      threadA, SIGNAL(SetMyText (QString, int)),
      p_str, SLOT (set_mes_str(QString, int)) );
      QObject::connect(
      threadB, SIGNAL(SetMyText (QString, int)),
      p_str, SLOT (set_mes_str(QString, int)) );

      }
      void ThreadAB::startOrStopThreadA()
      {
      if (threadA -> isRunning()) {
      threadA -> stop();
      threadAButton -> setText(tr("Start A"));
      } else {
      threadA -> start();
      threadAButton -> setText(tr("Stop A"));
      }
      }
      void ThreadAB::startOrStopThreadB()
      {
      if (threadB -> isRunning()) {
      threadB -> stop();
      threadBButton -> setText(tr("Start B"));
      } else {
      threadB -> start();
      threadBButton -> setText(tr("Stop B"));
      }
      }
      void ThreadAB::closeEvent(QCloseEvent *event)
      {
      threadA -> stop();
      threadB -> stop();
      threadA -> wait();
      threadB -> wait();
      event -> accept();
      }
      @

      MyString.h

      @
      #ifndef MySTRING_H
      #define MySTRING_H
      #include <QMessageBox>
      class MyString : public QObject
      {
      Q_OBJECT

      public:
      

      MyString();

      public slots:
      void set_mes_str(QString, int);
      void show_mes_str();

      signals:
      void mes_str_is_set();

      private:
      QString message_string;
      };
      #endif //MySTRING_H
      @

      MyString.cpp

      @
      #include "MyString.h"
      #include <QDebug>

      MyString::MyString(){
      QObject::connect(
      this, SIGNAL(mes_str_is_set()),
      this, SLOT (show_mes_str() ) );
      }

      void MyString::set_mes_str(QString thread_name, int running_number)
      {
      message_string = thread_name + "->" + running_number;
      qDebug() << "set_mes_str : message_string = " << message_string;
      emit mes_str_is_set();
      }
      void MyString::show_mes_str()/
      {
      QMessageBox msg;
      msg.setText(message_string);
      msg.exec();
      }
      @

      1 Reply Last reply Reply Quote 0
      • D
        DiIvPa last edited by

        Let me add: if you put in signal definition {} then compiler finds the function (not signal) ?!

        1 Reply Last reply Reply Quote 0
        • SGaist
          SGaist Lifetime Qt Champion last edited by

          Hi,

          You forgot the Q_OBJECT macro in your MyThread class.

          Don't forget to re-run qmake once you added it.

          Interested in AI ? www.idiap.ch
          Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

          1 Reply Last reply Reply Quote 0
          • D
            DiIvPa last edited by

            Dear SGaist, thank you very much ! It works now. With best wishes, Dmitri.

            1 Reply Last reply Reply Quote 0
            • SGaist
              SGaist Lifetime Qt Champion last edited by

              You're welcome !

              Since you signals are working now, please update the thread title prepending [solved] so other forum users may know a solution has been found :)

              Interested in AI ? www.idiap.ch
              Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

              1 Reply Last reply Reply Quote 0
              • First post
                Last post