c++ 自加或自减 的运算符重载

#include<iostream>using namespace std;class CDemo{private:int n;public:CDemo(int i=0):n(i){}CDemo operator++();//  ++d  成员函数 CDemo operator++(int);// d== operator int(){  return n;}///强制类型转换     int get_n(){    return n;}friend CDemo operator--(CDemo &t);// 全局函数friend CDemo operator--( CDemo &t,int );};CDemo CDemo::operator++(){n++;return *this;}CDemo CDemo::operator++(int){CDemo tmp(*this);n++;return tmp;}CDemo operator--( CDemo &d ){d.n--;return d;}CDemo operator--( CDemo &d, int ){     CDemo temp(d); d.n--; return temp;} int main(){CDemo d(5);cout<<(d--)<<endl; d++;cout<<(++d)<<endl;++d;return 0;}