C++ Dynamic Memory and Static Members

static int n is a variable that exist for the entire life of the program and is incremented / decremented upon the creation / destruction of CDummy.

As a consequence it tells the number of existing CDummy.

The main creates one, then 5 all together, then another on the heap, prints the number, destroy one (the one on the heap), prints again the number (one less as before) and - on return - destroy all the others.

A good variant can be this one:

// static members in classes
#include <iostream>
using namespace std;

class CDummy
{
    public:
        static int n;
        CDummy()  { n++; };
        ~CDummy() { n--; };
};

int CDummy::n=0;

int main ()
{
    cout << Dummy::n << endl;  //0
    {
        CDummy a;
        {
            cout << Dummy::n << endl; //1
            CDummy b[5];
            CDummy * c = new CDummy;
            cout << Dummy::n << endl; //7
        }
        cout << a.n << endl; //2
        delete c;
    }
    cout << CDummy::n << endl; //0
    return 0;
}

n is class share the static veriables shared betweenthem the address,and static veriables are global addr,the address will not be changed;my understanding.