类继承的静态成员是共享的

#include <iostream>
using namespace std;

class Base {
public:
	static int data;
};

int Base::data = 1;

class Derived1 : public Base {};

class Derived2 : public Base {};

int main()
{
	Base base;
	Derived1 D1;
	Derived2 D2;

	cout << base.data << endl;
	cout << D1.data << endl;
	cout << D2.data << endl;

	cout << "--------------------" << endl;;
	base.data = 2;
	cout << base.data << endl;
	cout << D1.data << endl;
	cout << D2.data << endl;

	return 0;
}