e mũ x

#include<iostream>
long giaithua(int n);
using namespace std;
int main()
{
    float x, saiso, e = 1, exp = 0;
    int n = 0;
    cout << "Nhap vao x = "; cin >> x;
    cout << "Nhap sai so = "; cin >> saiso;
    while (e >= saiso)
    {
        e = pow(float(x), n) / giaithua(n);
        exp += e;
        n++;
    }
    cout << "e^" << x << " = " << exp<<endl;
    return 0;
}
long giaithua(int n)
{
    if (n == 0 || n == 1)
        return 1;
    else
        return n*giaithua(n - 1);
}