重载ostream 左移操作符

1. 构造一个类

#include <iostream>
using namespace std;
class Overload
{
public:
	Overload();
    
private:
    int a;

};

2. 重载左移操作符

friend ostream& operator<<(ostream& os, Overload& ol);

3. 实现左移操作符

ostream& operator<<(ostream& os, Overload& ol)
{
    os << "a = " << ol.a <<endl;
    return os;
}

Overload::Overload()
{
    a = 1;
}

4. 调用左移操作符

Overload ol;
cout << ol;

5. 运行结果