自考新教材-p169

Posted 2021-03-12 duanqibo

源程序：

#include<iostream>
using namespace std;

class CDemo
{
private:
int n;
public:
CDemo(int i=0):n(i){}
CDemo & operator++(); //用于前置形式
CDemo operator++(int); //用于后置形式
operator int() {return n;}
friend CDemo & operator--(CDemo &);
friend CDemo operator--(CDemo &,int);
};

CDemo & CDemo::operator++() //前置++
{
n++;
return *this;
}

CDemo CDemo::operator++(int k) //后置++，多一个参数
{
CDemo tmp(*this); //记录修改前的对象
n++;
return tmp; //返回修改前的对象
}

CDemo & operator--(CDemo & d) //前置--
{
d.n--;
return d;
}

CDemo operator--(CDemo & d,int) //后置--
{
CDemo tmp(d);
d.n--;
return tmp;
}

int main()
{
CDemo d(10);
cout<<(d++)<<","; //等价于"d.operator++(0);"输出10
cout<<d<<","; //输出11
cout<<(++d)<<","; //等价于"d.operator++();"输出12
cout<<d<<","; //输出12
cout<<(d--)<<","; //等价于"d.operator--(0);"输出12
cout<<d<<","; //输出11
cout<<(--d)<<","; //等价于"d.operator--();"输出10
cout<<d<<","<<endl; //输出10
return 0;
}

 运行结果：