Biegral Blog

#include <iostream>
using namespace std;

class test
{
private:
	int x;
	int y;
	static int num;

public:
	void print()
	{
		cout << num << endl; // 非静态成员函数可以用静态成员数据
	}

	static int getNum()
	{
		// cout << x << endl;  // 错误:静态成员函数不能直接用非静态数据成员
		return num;
	}

	static void setNum(int n)
	{
		num = n;
	}
};

int test::num = 10; // 必须在类外初始化

int main()
{
    test a, b;

	cout << test::getNum() << endl;
	cout << a.getNum() << endl;
	cout << b.getNum() << endl;

	test::setNum(20);
	cout << test::getNum() << endl;
	cout << a.getNum() << endl;
	cout << b.getNum() << endl;

	a.setNum(30);
	cout << test::getNum() << endl;
	cout << a.getNum() << endl;
	cout << b.getNum() << endl;

	a.print();

	return 0;
}