question in signals and slots

Mihan

Hi all
As I know , a value coulde be changed in other function like:

void add(int &a)
{
    a++;
}

int main()
{
    int A = 0;
    add(&A);
    //then A will be 1;
}

Now when I send a value by quote( & )， then change it in the slot:

class calculate:public QObject
{
    Q_OBJECT
public:
    calculate();

signals: 
    void add(int &);
public slots:
    void on_add(int &number);
};

void calculate::on_add(int &a)
{
    a++;
}


calculate::calculate()
{
    int A = 0;
    connect(this, SIGNAL(add(int &)), this , SLOT(on_add(int &)));
    
    emit add(&A);
    
   //then A will be 1;
}

Is that right?

Best regards.
Mihan

Christian Ehrlicher

Since signals and slots can be asynchronous you can't pass a non-const reference to a slot.