【C++】运算符重载-加号

对已有的运算符重新进行定义，赋予其另一种功能，以适应不同的数据类型

• 总结:

1. 对于内置的数据类型的表达式的运算符是不可能改变的
2. 不要滥用运算符重载

直接进行加法运算

• 报错

  #include <iostream>
  using namespace std;
  
  class Person {
  public:
  	int m_A;
  	int m_B;
  };
  int main(){
  	Person p1;
  	Person p2;
  	p1.m_A = 10;
  	p2.m_A = 20;
  	p1.m_B = 30;
  	p2.m_B = 40;
  	Person p3 = p1 + p2;//报错
  	cout << "p3.m_A=" << p3.m_A << endl;
  	cout << "p3.m_B=" << p3.m_B << endl;
  	return 0;
  }

使用自己的成员函数进行运算

• 正常

#include <iostream>
using namespace std;

class Person {
public:
	Person personAddPerson(Person &p) {
		Person temp;
		temp.m_A = this->m_A + p.m_A;
		temp.m_B = this->m_B + p.m_B;
		return temp;
	}
	int m_A;
	int m_B;
};
int main(){
	Person p1;
	Person p2;
	p1.m_A = 10;
	p2.m_A = 20;
	p1.m_B = 30;
	p2.m_B = 40;
	Person p3 = p1.personAddPerson(p2);//正常
	cout << "p3.m_A=" << p3.m_A << endl;
	cout << "p3.m_B=" << p3.m_B << endl;
	return 0;
}

• 不可写成p3=p1+p2;

使用编译器提供的的函数名

• 可写成p3=p1+p2;

成员函数

#include <iostream>
using namespace std;

class Person {
public:
	Person operator+ (Person &p) {
		Person temp;
		temp.m_A = this->m_A + p.m_A;
		temp.m_B = this->m_B + p.m_B;
		return temp;
	}
	int m_A;
	int m_B;
};
int main(){
	Person p1;
	Person p2;
	p1.m_A = 10;
	p2.m_A = 20;
	p1.m_B = 30;
	p2.m_B = 40;
	Person p3 = p1 + p2;//正常
    //相当于Person p3=p1.operator+(p2);
	cout << "p3.m_A=" << p3.m_A << endl;
	cout << "p3.m_B=" << p3.m_B << endl;
	return 0;
}

全局函数

#include <iostream>
using namespace std;

class Person {
public:

	int m_A;
	int m_B;
};
Person operator+ (Person& p1,Person &p2) {
	Person temp;
	temp.m_A = p1.m_A + p2.m_A;
	temp.m_B = p1.m_B + p2.m_B;
	return temp;
}
int main(){
	Person p1;
	Person p2;
	p1.m_A = 10;
	p2.m_A = 20;
	p1.m_B = 30;
	p2.m_B = 40;
	Person p3 = p1 + p2;//正常
    //相当于Person p3=operator+(p1,p2);
	cout << "p3.m_A=" << p3.m_A << endl;
	cout << "p3.m_B=" << p3.m_B << endl;
	return 0;
}

自定义 + int

#include <iostream>
using namespace std;

class Person {
public:

	int m_A;
	int m_B;
};
Person operator+ (Person& p1,int num) {
	Person temp;
	temp.m_A = p1.m_A + num;
	temp.m_B = p1.m_B + num;
	return temp;
}
int main(){
	Person p1;
	Person p2;
	p1.m_A = 10;
	p2.m_A = 20;
	p1.m_B = 30;
	p2.m_B = 40;
	Person p3 = p1 + 50;//正常
	cout << "p3.m_A=" << p3.m_A << endl;
	cout << "p3.m_B=" << p3.m_B << endl;
	return 0;
}