#include <iostream>
#include <sstream>
#include <fstream>
#include <map>

class ConfigFile
{
    public:
        ConfigFile(const std::string& filename)
        {
            std::ifstream file(filename.c_str());
            std::string line;
            while( std::getline(file, line) )
            {
                std::istringstream iss(line);
                std::string key, value;
                iss >> key;
                iss >> value;
                m_conf.insert( std::pair<std::string, std::string>(key,value) );
            }
            file.close();
        }

        template<typename T>
        const T& operator[](const std::string& key)
        {
            std::ostringstream oss(m_conf[key]);
            T result;
            result << oss;
            return result;
        }

    private:
        std::map<std::string, std::string> m_conf;
};


int main()
{
    ConfigFile cf("config.in");
    double altitude = cf["altitude"];

    std::cout << altitude << std::endl;

    return 0;
}