c++分数的重载加减乘除

#include <iostream>
using namespace std;
class Fenshu
{
private:
int fenmu;
int fenzi;

public:
Fenshu(){fenzi=0;fenmu=0;}
Fenshu(int z,int m){fenzi=z;fenmu=m;}
void simplify()
{
int m,n,r;  
m=fenzi;
n=fenmu;
if(m<n)
{
r=m;
m=n;
n=r;
}

while(n!=0)  // 求m，n的最大公约数   
{  
r=m%n;
m=n;  
n=r;  
}