c++修饰符重载

主要有两种方式：利用友元、类成员方法。

#include <iostream>
using namespace std;

/**
*演示修饰符重载
*一般都用成员方法重载
*特殊的没有办法修改核心库的用友元的方法来重载 例如<<
*/
class Chicken
{
private:
    int weight;
public:
    Chicken(int weight)
    {
        this->weight = weight;
    }
    ~Chicken()
    {
        delete this;
    }
    int getWeight();
    void setWeight(int weight);
    friend int operator +(Chicken & a,Chicken & b);
    int operator -(Chicken & a);
    friend int operator ++(Chicken & a);
    int operator --();
    friend int operator ++(Chicken & a,int);
    int operator --(int);
    friend ostream & operator << (ostream & out,Chicken & a);
};

int Chicken::getWeight()
{
    return this->weight;
}

void Chicken::setWeight(int weight)
{
    this->weight = weight;
}

int operator +(Chicken & a,Chicken & b)
{
    return a.weight+b.weight;
}

int Chicken::operator -(Chicken & a)
{
    return this->weight-a.weight;
}

int operator ++(Chicken & a)
{
    a.weight ++;
    return a.weight;
}

int Chicken::operator --()
{
    this->weight --;
    return this->weight;
}

int operator ++(Chicken & a,int)
{
    int b = a.weight;
    a.weight ++;
    return b;
}

int Chicken::operator --(int)
{
    int b = this->weight;
    this->weight --;
    return b;
}

ostream & operator << (ostream & out,Chicken & a)
{
    cout << "The weight is: " << a.weight;
    return out;
}


int main()
{
    Chicken a(20);
    Chicken b(10);
    cout << a.getWeight() << endl;
    cout << b.getWeight() << endl;
    cout << a-b << endl;
    cout << a+b << endl;
    cout << ++a << endl;
    cout << a.getWeight() << endl;
    cout << --a << endl;
    cout << a.getWeight() << endl;
    cout << a++ << endl;
    cout << a.getWeight() << endl;
    cout << a-- << endl;
    cout << a.getWeight() << endl;
    cout << a << endl;
    return 0;
}