用迭代器求vector<double>中元素的和，for语句写循环

#include <iostream>
#include<vector>
using namespace std;

double sum(vector<double> ivec )

{       vector<double>::iterator iter;
double result=0;
    for(vector<double>::iterator iter=ivec.begin();iter!=ivec.end();++iter)
        result+=*iter;
    return result;
}

int main()
{
    vector<double>ivec1;
    cout<<"please input double type for vector(ctrl+z to end):"<<endl;
    double val;
    while(cin>>val){
        ivec1.push_back(val);
    }
    cout<<sum(ivec1)<<endl;
    return 0;
}