static

 

 

//为防止static变量被多次declaration    int Dummy::n=0;放于类外

#include <iostream>
using namespace std;

class Dummy {
public:
static int n;
Dummy () { n++; };
};

int Dummy::n=0;

int main () {
Dummy a;
Dummy b[5];
cout << a.n << '\n';
Dummy * c = new Dummy;
cout << Dummy::n << '\n';
delete c;
return 0;
}