求1!+2!+3!+......+n!的和 -----C++-----

#include<iostream>
using namespace std;
int function(int x)
{
    int i,sum=;
    for(i=;i<=x;i++)
        sum=sum*i;
    return sum;
}
int main()
{
    int a,i,b=;
    cout<<"输入N(求N的阶乘):";
    cin>>a;
    for(i=;i<=a;i++)
        b+=function(i);
    cout<<"N的阶乘是:"<<b<<endl;
    return ;
}