math - C++ program to calculate e^x -

i know there many examples of problem tried write different 1 myself. using taylor series e^x = 1 + x/1! + x^2/2! + x^3/3! + ...... code compiles , runs wont output correct answer imputes , i'm not sure why. usable code or should scrap it?

    #include <iostream>     #include <cmath>      using namespace std;     int main()    {         double final,power,end_n = 1.0,e=1.0,x=2.0, n;         cout<< "n: ";        // enter 5 test         cin>> n;         while (n>1){             power = pow(x,n);             end_n = end_n*n;             e= (power/end_n)+e;             n--;         }         final =e+x;         cout<< final;       return 0;     } 

i have no idea reasoning is, @ all. code particular expansion trivially simple:

double x; cin >> x;  double oldres, res=1, top=1, bottom=1; int iter=1;  {   oldres=res;                           // calculate difference between iterations    ++iter;                               // next iteration   top*=x;                               // multiply 1 x each iteration   bottom*=(iter-1);                     // multiply iteration number each iteration   res+=top/bottom;                      // , add fraction result } while(fabs(res-oldres)>.1);           // while difference still large  cout << res;                            // done, show result