how to count the number of objects created in c++

Question

how to count the number of objects created in c++

pls explain with a simple example

Answer 1

update on code as opposed to "stefanB" solution, some variables are in protected access mode and will not be accessible.

template 
    struct counter
    {
        counter()
        {
            std::cout << "object created"<< endl;
            this->objects_created++;
            this->objects_alive++;
        }

        counter(const counter& test)
        {
            std::cout << "object created:" << test << endl;
             this->objects_created++;
             this->objects_alive++;
        }

        static int getObjectsAlive(){
            return objects_alive;
        }

        static int getObjectsCreated(){
            return objects_created;
        }


    protected:
        virtual ~counter()
        {
            std::cout << "object destroyed"<< endl;
            --objects_alive;
        }
        static int objects_created;
        static int objects_alive;
    };
    template  int counter::objects_created( 0 );
    template  int counter::objects_alive( 0 );

    class X : counter
    {
        // ...
    };

    class Y : counter
    {
        // ...
    };
    
    Usage for completeness:
    
        int main()
        {
            X x1;
        
            {
                X x2;
                X x3;
                X x4;
                X x5;
                Y y1;
                Y y2;
            }   // objects gone
        
            Y y3;
         
    cout << "created: "
         << " X:" << counter::getObjectsCreated()
         << " Y:" << counter::getObjectsCreated()  //well done
         << endl;

    cout << "alive: "
         << " X:" << counter::getObjectsAlive()
         << " Y:" << counter::getObjectsAlive()
         << endl;
        }