C++类与对象之运算符重载详解

#include <iostream>
using namespace std;
class Person {
public:
	// 构造函数
	Person(int num1, int num2){
		this->num1 = num1;
		this->num2 = num2;
	}
	// 加法函数
	Person operator+(const Person &p){
		Person temp(0, 0);
		temp.num1 = this->num1 + p.num1;
		temp.num2 = this->num2 + p.num2;
		return temp;
	}
	// 打印输出
	void printMessage() {
		cout << "num1 = " << num1 << " num2 = " << num2 << endl;
	}
private:
	int num1;
	int num2;
};
void func() {
	Person p1(1, 2);
	Person p2(3, 4);
	Person p3 = p1.operator+(p2); // 可以简化为 Person = p1 + p2;
	p3.printMessage(); // num1 = 4 num2 = 6
	Person p4 = p3 + p2;
	p4.printMessage(); // num1 = 7 num2 = 10
}
int main() {
	func();
	system("pause");
	return 0;
}

#include <iostream>
using namespace std;
class Person {
public:
	// 构造函数
	Person(int num1, int num2){
		this->num1 = num1;
		this->num2 = num2;
	}
	// 左移运算符 p.operator<<(cout); 简化版本 p << cout
	void operator <<(ostream &cout) {
		cout << "num1 = " << num1 << " num2 = " << num2 << endl;
	}
private:
	int num1;
	int num2;
};
void func() {
	Person p1(1, 2);
	p1.operator<<(cout); // 简化为 p1 << cout
	Person p2(3, 4);
	p2 << cout;
}
int main() {
	func();
	// outputs:num1 = 1 num2 = 2
	//		   num1 = 3 num2 = 4
	system("pause");
	return 0;
}

#include <iostream>
using namespace std;
class Person {
	// 友元
	friend ostream& operator <<(ostream &cout, Person &p);
public:
	// 构造函数
	Person(int num1, int num2){
		this->num1 = num1;
		this->num2 = num2;
	}
private:
	int num1;
	int num2;
};
// 左移运算符 p.operator<<(cout); 简化版本 p << cout
ostream& operator <<(ostream &cout, Person &p) {
	cout << "num1 = " << p.num1 << " num2 = " << p.num2;
	return cout;
}
void func() {
	Person p1(1, 2);
	operator<<(cout, p1); // 简化为 cout << p1;
	cout << endl;
	cout << p1 << " 你是猪！" << endl;
}
int main() {
	func();
	// outputs:num1 = 1 num2 = 2
	//		   num1 = 1 num2 = 2 你是猪！
	system("pause");
	return 0;
}

#include <iostream>
using namespace std;
class MyInteger {
	//friend ostream& operator <<(ostream &cout, MyInteger &p);
	friend ostream& operator <<(ostream &cout, MyInteger p);
public:
	// 构造函数
	MyInteger(){
		this->m_num = 0;
	}
	// 重载前置递增运算符
	MyInteger& operator++() {
		++this->m_num;
		return *this;
	}
	// 重载后置递增运算符
	MyInteger operator++(int) { // int 是占位参数，用于区分前置和后置递增
		MyInteger temp = *this;
		++this->m_num;
		return temp;
	}
private:
	int m_num;
};
// 用于前置递增，左移运算符 p.operator<<(cout); 简化版本 p << cout
//ostream& operator <<(ostream &cout, MyInteger &p) {
//	cout << "m_num = " << p.m_num;
//	return cout;
/