求教大神一个编程：利用C++函数重载,定义三个函数的乘法,实数乘法,整数乘法,复数乘法

#include
typedef struct {int m,int n}Complex;
double mult(double &a,double &b){return a*b;}
long mult(long &a,long &b){return a*b};
Complex mult(Complex &a,Complex &b)
{
Complex c;
c.m=a.a*b.a-a.b*b.b;
c.n=b.b*a.a+a.b*b.a;
return c;
}
//主程序略