// 重载 C++ 的 << 输出流运算符
#include <iostream>
#include <cstring>
#include <cstdlib>

using namespace std;

class A
{
    friend ostream &operator<<(ostream &cout, A &a);

private:
    int x, y;

public:
    A(int x, int y) : x(x), y(y) {}
};

// << 输出运算符重载
ostream &operator<<(ostream &cout, A &a)
{
    // x, y 是 A 类的私有成员
    cout << "a.x : " << a.x << ", a.y : " << a.y << endl;
    return cout;
}

int main()
{
    A a1(1, 2);
    cout << a1;
    return 0;
}