Qt C++ customized slot does not work

Question

I am trying to connect a button with a slot defined in an external class called simu. The slot is a function called startSimu(). The object simulation is instantiated in the same class where I hope to connect the button. Below is the code:

QPushButton *btn1 = new QPushButton("start simulation");
simu simulation;
QObject::connect(btn1, SIGNAL(clicked()), &simulation, SLOT(startSimu()));

The code compiles and runs, but when I click on the button nothing happens. The function startSimu() is the following:

void simu::startSimu() {
    std::cout << "aaaa" << std::endl;
}

The header of the simu class:

#ifndef SIMU_H
#define SIMU_H

#include <QObject>

class simu : public QObject
{
    Q_OBJECT

public:
    simu();
    double timer() {return time;}

public slots:
    void startSimu();


private:
    double time;
};

#endif // SIMU_H

I hope someone has a clue or a hint! Thanks

Answer 1

It looks like your simulation object destroyed before the slot is called, because you allocated it in the stack:

simu simulation; // Will be destroyed as the execution leave the scope.
QObject::connect(btn1, SIGNAL(clicked()), &simulation, SLOT(startSimu()));

To fix this you will need probably do the following:

simu *simulation = new simu; // Will be destroyed soon
QObject::connect(btn1, SIGNAL(clicked()), simulation, SLOT(startSimu()));

Please do not forget to delete the simulation object when needed.