class of factorial

#include<iostream.h>
#include<conio.h>
class factorial
{    public:
int n;
factorial(int a)
{
n=a;
}
void f()
  {
int f=1;
for(int i=1;i<=n;i++)
{
f=f*i;
}
cout<<f;
}
};
void main()
{
clrscr();
int n;
cout<<"enter the no";
cin>>n;
factorial obj(n);
obj.f();
getch();
}