C++ 运算符重载（二）之左移运算符重载

class Person {
public:
  Person(int a, int b)  {    this->m_A = a;    this->m_B = b;  }  //利用成员函数实现左移运算符：p.operator<<(cout)简化版本p << cout 无法实现cout在左边。  //成员函数 p << p 不是我们想要的效果，想要cout<<p  void operator<<(Person& p){      cout << "a:" << p.m_A << " b:" << p.m_B;  }
private:  int m_A;  int m_B;};
void test() {
  Person p1(10, 20);  p1 << p1;//p1.operator<<(p1);}
int main() {
  test();
  system("pause");
  return 0;}

class Person {    //全局函数做友元，告诉编译器 operator<<全局函数 是 Person类的好朋友，可以访问类中的私有内容  friend void operator<<(ostream& out, Person& p);
public:
  Person(int a, int b)  {    this->m_A = a;    this->m_B = b;  }
private:  int m_A;  int m_B;};
//只能全局函数实现左移重载//ostream对象只能有一个void operator<<(ostream& out, Person& p) {  out << "a:" << p.m_A << " b:" << p.m_B;}
void test() {
  Person p1(10, 20);  cout << p1;}
int main() {
  test();
  system("pause");
  return 0;}

class Person {  friend ostream& operator<<(ostream& out, Person& p);
public:
  Person(int a, int b)  {    this->m_A = a;    this->m_B = b;  }private:  int m_A;  int m_B;};
//只能全局函数实现左移重载//ostream对象只能有一个,所以添加&取地址,cout的定义类型为ostreamostream& operator<<(ostream& out, Person& p) {  out << "a:" << p.m_A << " b:" << p.m_B;  return out;//返回cout需要更改函数头为ostream}
void test() {
  Person p1(10, 20);
  cout << p1 << "hello world" << endl; //链式编程。}
int main() {
  test();
  system("pause");
  return 0;}