重载操作符

一、类外重载操作符（使用友元函数）

class Complex
{
    int a;
    int b;
public:
    Complex(int a = 0, int b = 0)
    {
        this->a = a;
        this->b = b;
    }

　　friend Complex operator + (const Complex& p1, const Complex& p2);//友元函数，使类之外的函数能够访问私有属性

　　　　　　　　　　　　　　//两个参数，分别对应+的左右参数

}；

Complex operator + (const Complex& p1, const Complex& p2)
{
　　Complex ret;
　　ret.a = p1.a + p2.a;
　　ret.b = p1.b + p2.b;
　　return ret;
}

int main()
{

　　Complex c1(1, 2);

　　Complex c2(3, 4);
　　Complex c3 = c1 + c2; // operator + (c1, c2)
　　printf("c3.a = %d, c3.b = %d\n", c3.getA(), c3.getB());
　　return 0;
}

二、类函数重载操作符

class Complex
{
    double a;
    double b;
public:
    Complex(double a = 0, double b = 0);
    double getA();
    double getB();
    double getModulus();
   
    Complex operator + (const Complex& c);//只有一个参数，对应+的右操作数，左操作数默认为this
    Complex operator - (const Complex& c);
    Complex operator * (const Complex& c);
    Complex operator / (const Complex& c);
   
    bool operator == (const Complex& c);
    bool operator != (const Complex& c);
   
    Complex& operator = (const Complex& c);
};

Complex::Complex(double a, double b)
{
    this->a = a;
    this->b = b;
}

double Complex::getA()
{
    return a;
}

double Complex::getB()
{
    return b;
}

double Complex::getModulus()
{
    return sqrt(a * a + b * b);
}

Complex Complex::operator + (const Complex& c)
{
    double na = a + c.a;
    double nb = b + c.b;
    Complex ret(na, nb);
   
    return ret;
}

Complex Complex::operator - (const Complex& c)
{
    double na = a - c.a;
    double nb = b - c.b;
    Complex ret(na, nb);
   
    return ret;
}

Complex Complex::operator * (const Complex& c)
{
    double na = a * c.a - b * c.b;
    double nb = a * c.b + b * c.a;
    Complex ret(na, nb);
   
    return ret;
}

Complex Complex::operator / (const Complex& c)
{
    double cm = c.a * c.a + c.b * c.b;
    double na = (a * c.a + b * c.b) / cm;
    double nb = (b * c.a - a * c.b) / cm;
    Complex ret(na, nb);
   
    return ret;
}
   
bool Complex::operator == (const Complex& c)
{
    return (a == c.a) && (b == c.b);
}

bool Complex::operator != (const Complex& c)
{
    return !(*this == c);
}
   
Complex& Complex::operator = (const Complex& c)
{
    if( this != &c )
    {
        a = c.a;
        b = c.b;
    }
   
    return *this;
}