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;}