Hi, I have the following code section: po::options_description config; config.add_options() ( "HOST", po::value<string>(&host) ) ( "USER", po::value<string>(&user) ) ( "PASSWD", po::value<string>(&passwd) ) ( "DATABASE", po::value<string>(&database) ) ( "PORT", po::value<int>(&port) ) ( "VERTEX.WEIGHT", po::value<string>()->zero_tokens() ); po::variables_map vm; ifstream ifs( "myfile.conf" ); store( parse_config_file( ifs, config ), vm ); notify( vm ); If in myfile.conf I leave WEIGHT blank like this [VERTEX] WEIGHT = I get the following error message: terminate called after throwing an instance of 'boost::exception_detail::clone_implboost::program_options::invalid_syntax

' what(): no value given in 'WEIGHT =' Aborted

Someone can tell whats is wrong? Thanks Marcio