How about

    #include <iostream>
    #include <iterator>
    #include <algorithm>
    #include <fstream>
    #include <string>
    #include <vector>

    using namespace std;

    struct Line
    {
        string lineData;
        
        operator string() const
        {
            return lineData;
        }
    };

    std::istream& operator>>(std::istream& str,Line& data)
    {
        getline(str,data.lineData);
        return str;
    }

    int main(int argc, const char * argv[])
    {
        ifstream ifile(argv[1]);
        ofstream ofile(argv[2]);
        vector<string> data;
        copy(istream_iterator<Line>(ifile), istream_iterator<Line>(), back_inserter(data));
        sort(data.begin(), data.end());
        copy(data.begin(),data.end(), ostream_iterator<string>(ofile, "\n"));
        return 0;
    }

And to inform everyone. Cling as a C++ REPL exists. http://root.cern.ch/drupal/content/cling