1. 基本概念
所谓重载，就是重新赋予新的含义。不仅函数可以重载，运算符也可以重载。
运算符重载的本质是一个函数。
接下来我们来推演一下运算符重载函数进化为成员函数的过程：
1）相加函数作为普通函数
class Complex
{
public:
int a, b;
public:
Complex(int a = 0, int b = 0)
{
this->a = a;
this->b = b;
}
};
Complex Add(Complex &c1, Complex &c2)
{
Complex tmp(c1.a + c2.a, c1.b + c2.b);
return tmp;
}
int main()
{
Complex c1(1, 2), c2(3, 4);
// 1 普通函数
Complex c3 = Add(c1, c2);
return 0;
}
2）相加函数作为友元函数
class Complex
{
public:
int a, b;
friend Complex operator+(Complex &c1, Complex &c2);
public:
Complex(int a = 0, int b = 0)
{
this->a = a;
this->b = b;
}
};
Complex operator+(Complex &c1, Complex &c2)
{
Complex tmp(c1.a + c2.a, c1.b + c2.b);
return tmp;
}
int main()
{
Complex c1(1, 2), c2(3, 4);
// 2 友元函数
Complex c3 = operator+(c1, c2);
return 0;
}
3）相加函数作为类成员函数
class Complex
{
public:
int a, b;
Complex operator+(Complex &c2)
{
Complex tmp;
tmp.a = this->a + c2.a ;
tmp.b = this->b + c2.b ;
return tmp;
}
public:
Complex(int a = 0, int b = 0)
{
this->a = a;
this->b = b;
}
};
int main()
{
Complex c1(1, 2), c2(3, 4);
// 3 成员函数
Complex c3 = c1 + c2;
return 0;
}
未完待续。。。。。。
原文：https://www.cnblogs.com/yanghh/p/12945941.html