Object Counter in C++

cpp-object-counter-using-CRTP.cpp

/*CRTP -> Curiously recurring template pattern*/
/*
  CRTP is when a class A has a base class which is a template specialization for the class A itself.
  
  eg:
  template <class T> 
  class X{...};
  class A : public X<A> {...};
  (source: https://stackoverflow.com/questions/4173254/what-is-the-curiously-recurring-template-pattern-crtp)
*/

#include <iostream>
using namespace std;

template <class T>
class Demo{
  private:
      static int count;
  public:
    Demo(){
       count++;
    }  
    Demo(const Demo &d){
       count++;
    }   
    ~Demo(){
       count--;
    }    
    static int GetCount(){
        return count;
    }
};

template<class T> 
int Demo<T>::count = 0; 

class MyClass : private Demo<MyClass>{
   public:
      using Demo<MyClass>::GetCount;
};

int main(){
    MyClass m;
    MyClass m1;
    MyClass m2;
    
    cout << "Total no of objects created: " << m.GetCount() << endl;
    return 0;
}

/* (cource: https://stackoverflow.com/questions/1926605/how-to-count-the-number-of-objects-created-in-c) */

cpp-simple-object-counter.cpp

#include <iostream>
using namespace std;

class Demo{
    private:
        static int objCount;
    
    protected:
        int num;
        char a[20];
    
    public:
        Demo(){
            objCount++;
        }
        
        static void printCount(){
            cout << "Total number of objects created: " << objCount;
        }
        
        void echo(){
            cout << "Hello World" << endl;
        }
};

int Demo :: objCount = 0; 

int main()
{
  Demo d;
  d.echo();
  Demo d1;
  Demo d2;
  d.printCount();
  return 0;
}