How do I write this very simple program?

Often, especially at the start of semesters, I get a lot of questions about how to write very simple programs. Typically, the problem to be solved is to read in a few numbers, do something with them, and write out an answer. Here is a sample program that does that:
PHP Code:
#include<iostream>
    #include<vector>
    #include<algorithm>
    using namespace std;

    int main()
    {
        vector<double> v;

        double d;
        while(cin>>d) v.push_back(d);    // read elements
        if (!cin.eof()) {        // check if input failed
            cerr << "format error\n";
            return 1;    // error return
        }

        cout << "read " << v.size() << " elements\n";

        reverse(v.begin(),v.end());
        cout << "elements in reverse order:\n";
        for (int i = 0; i<v.size(); ++i) cout << v[i] << '\n';

        return 0; // success return
    }