[Boost-users] program_option error

What am I doing wrong? I get error 'boost::program_options::typed_value<T> *boost::program_options::value(T *)' : expects 1 arguments - 0 provided class options { public: unsigned int _option1; int _option2; void parse_options() { boost::program_options::options_description config; config.add_options() ("set1", boost::program_options::value<&_option1>()->default_value(200), "seting 1") ("set2", boost::program_options::value<&_option2>()->default_value(300), "seting 2"); } }; Thanks for help