#include<cmath>
using namespace std;
int f(int n){
    if(n=1)  return 1;
             return n*f(n-1);
             }
int main(){
    double sum=1,item=1;int n;
    double g = double Pow(double i,double n);
    cout<<"please input a number n=:";
    cin>>n;
   
    for(int i=1,sign=1;i<=n;i++,sign*=-1,g,f(n)){
            item=sign*g/f(n);
            sum+=item;
            }
            cout<<"sum is:"<<sum<<endl;
            system ("pause");
            }
要求是计算1+x-x^2/2!+x^3/3!-……（-1）^n+1* x^n/n!
我写的哪里有问题呢    编译通不过