错误 C1083:无法打开包含文件:'stdafx.h'

When I compiled this program (from C++ Programming Language 4th edition):

main.cpp

#include <stdafx.h>
#include <iostream>
#include <cmath>
#include "vector.h"
using namespace std;

double sqrt_sum(vector&);

int _tmain(int argc, _TCHAR* argv[])
{
    vector v(6);
    sqrt_sum(v);
    return 0;
}

double sqrt_sum(vector& v)
{
    double sum = 0;
    for (int i = 0; i != v.size(); ++i)
        sum += sqrt(v[i]);
    return sum;
}

vector.cpp

#include <stdafx.h>
#include "vector.h" 

vector::vector(int s)
:elem{ new double[s] }, sz{ s }
{
}
double& vector::operator[](int i)
{
    return elem[i];
}
int vector::size()
{
    return sz;
}

vector.h

#include <stdafx.h>
class vector{
public:
    vector(int s);
    double& operator[](int i);
    int size();
private:
    double* elem;
    int sz;
};

它给了我这些错误:

我在 Windows 7 上的 Microsoft Visual Studio 2013 上运行它.如何修复它?