#include "stdafx.h"
#include <algorithm>
#include <iomanip>
#include <ios>
#include <iostream>
#include <string>
#include <vector>

using std::cin;             using std::sort;
using std::cout;            using std::streamsize;
using std::endl;            using std::string;
using std::setprecision;    using std::vector;

int main()
{
   
    cout << "Please enter your first name: ";
    string name;
    cin >> name;
    cout << "Hello, " << name << "!" << endl;

   
    cout << "Please enter your midterm and final exam grades: ";
    double midterm, final;
    cin >> midterm >> final;

   
    cout << "Enter all your homework grades, "
            "followed by end-of-file: ";

    vector<double> homework;
    double x;
    while (cin >> x)
        homework.push_back(x);

   
    typedef vector<double>::size_type vec_sz;
    vec_sz size = homework.size();
    if (size == 0) {
        cout << endl << "You must enter your grades.  "
                        "Please try again." << endl;   
        return 1;
    }

    sort(homework.begin(), homework.end());

   
    vec_sz mid = size/2;
    double median;
    median = size % 2 == 0 ? (homework[mid] + homework[mid-1]) / 2
                           : homework[mid];

   
    streamsize prec = cout.precision();
    cout << "Your final grade is " << setprecision(3)
         << 0.2 * midterm + 0.4 * final + 0.4 * median
         << setprecision(prec) << endl;

    return 0;
}

这个程序，我是按书上编的，但是不知道怎么运行，运行到第三步就不往下走了，求高手指点，我是新手，二专选的计算机，课本又是全英文的，实在费劲，求高手指点啊
另外说一下，我是文科生，之前没有任何编程基础，连C语言也不会，

可是，我是按课本上一步步来的啊，我都不知道怎么办了

你编译的时候出错了吗，应该没有吧，我是能编译成功的，就是不知道怎么运行