I'm writing a program that send an UDP frame every 10 mS. Here's how my program is supposed to work :
I've got a client class :
//Constructor
clientSupervision::clientSupervision()
{
}
void clientSupervision::sendDataUDP(){
//Create a frame and send it
...
}
void clientSupervision::sendDataUDPTimer(int timer){
QTimer *tempsEnvoieTrameSupervision = new QTimer();//Create a timer
tempsEnvoieTrameSupervision->setInterval(timer);//Set the interval
//Mise en place des connections
QObject::connect (tempsEnvoieTrameSupervision,SIGNAL (timeout()),this, SLOT (envoiTrameSupervision())); //Connect the timer to the function
tempsEnvoieTrameSupervision->start();// Start the timer
}
//Call sendDataUDP
void clientSupervision::envoiTrameSupervision(){
std::cout << "Envoi de la trame de supervision";
sendDataUDP();
}
My header file of clienSupervision.h :
#ifndef CLIENTSUPERVISION_H
#define CLIENTSUPERVISION_H
#include <winsock2.h> // pour les fonctions socket
#include <cstdio> // Pour les Sprintf
#include "StructureSupervision.h"
#include "utilitaireudp.h"
#include <QTimer>
#include <QObject>
#include <iostream>
class clientSupervision
{
Q_OBJECT
public:
clientSupervision();
void sendDataUDP();
void sendDataUDPTimer(int timer);
public slots:
void envoiTrameSupervision();
};
#endif // CLIENTSUPERVISION_H
Then I use this in my main :
int main(int argc, char *argv[])
{
clientSupervision c;
c.sendDataUDPTimer(10);
QCoreApplication a(argc, argv);
return a.exec();
}
I've got the error :
no matching function for call to 'QObject::connect(QTimer*&, const char*, clientSupervision* const, const char*)
I don't understand why the connect function can't find a matching function.
What should I change?
László Papp :
There can be several reasons for the issue in general:\n\n\nYou do not inherit QObject.\nYou do not have the Q_OBJECT macro in your class.\nYou do not define the method as slot in your header file where the class is declared.\n\n\nYour issue is the first which can be seen here:\n\nclass clientSupervision\n\n\nYou should change your code to:\n\nclass clientSupervision : public QObject\n// ^^^^^^^^^^^^^^^^\n\n\nOf course, the constructor implementation and signature would need to change, too, as follows:\n\nexplicit clientSupervision(QObject *parent = Q_NULL_PTR) : QObject(parent) { ... }\n\n\nIn addition, you seem to leak your QTimer instance as it does not get the parent as a parameter to the constructor.\n\nFurthermore, the QObject:: scope is needless in your code as your class ought to inherit QObject directly or indirectly either way.\n\nEven more, I would highly encourage you to utilize the new signal-slot syntax.",
2014-06-25T13:31:49
Peter Mitrano :
Another possible cause of this error is trying to connect to a slot which is overloaded. For example, this well cause the same error\n\nQObject::connect(this,\n &MazeWidget::MyUpdate,\n this, \n &QWidget::update,\n Qt::QueuedConnection);\n\n\nBut not if you explicitely cast:\n\nQObject::connect(this,\n &MazeWidget::MyUpdate,\n this,\n static_cast<void (QWidget::*)()>(&QWidget::update),\n Qt::QueuedConnection);\n",
2017-09-11T03:56:55
2NinerRomeo :
Here's another one that snuck up on me: The class of the slot object had been forward declared in the header, but not defined in the implementation by including its header.",
2018-11-30T00:47:35