c++语言友元函数和成员函数对运算符重载

#include<iostream>
using namespace std;
/******************************************/
/*use member function to overload operator*/
/******************************************/
class RMB{
public:
RMB(unsigned int d, unsigned int c);
RMB operator + (RMB&);
RMB& operator ++();
void display(){
cout <<"use member function overload operator"<<(yuan+jf/100.0) << endl;
}
protected:
unsigned int yuan;
unsigned int jf;
};
RMB::RMB(unsigned int d, unsigned int c){
yuan = d;
jf = c;
while (jf >= 100){
yuan++;
jf -= 100;
}
}
RMB RMB::operator + (RMB& s){
unsigned int c = jf + s.jf;
unsigned int d = yuan + s.yuan;
RMB result(d, c);
return result;
}

RMB& RMB::operator ++(){
jf++;
if (jf >= 100){
jf -= 100;
yuan++;
}
return *this;
}
/******************************************/
/*use friend function to overload operator*/
/******************************************/
class RMBf{
public:
RMBf(unsigned int b, unsigned int a);
friend RMBf operator+(RMBf&, RMBf&);  //two operands  while member function use just one operand
friend RMBf& operator++(RMBf&);       //one operands  while member function use no operand
void display(){ cout <<"use friend function to overload operator"<<(yuan+jf/100.0) << endl; }
protected:
unsigned int yuan;
unsigned int jf;
};
RMBf::RMBf(unsigned int b, unsigned int a){
yuan = b;
jf = a;
while (jf >= 100){
yuan++;
jf -= 100;
}
}
RMBf operator + (RMBf& s1, RMBf& s2){  //needn't class name::operator name, more simple
unsigned int c = s1.jf + s2.jf;
unsigned int d = s1.yuan + s2.yuan;
RMBf result(d, c);
return result;
}

RMBf& operator ++(RMBf& s){
s.jf++;
if (s.jf >= 100){
s.jf -= 100;
s.yuan++;
}
return s;
}
void main(){
RMB d1(1, 60);
RMB d2(2, 50);
RMB d3(0, 0);
d3 = d1 + d2;
++d3;
d3.display();

RMBf f1(1, 60);
RMBf f2(2, 50);
RMBf f3(0, 0);
f3 = f1 + f2;
++f3;
f3.display();
int i;
cin >> i;
}