Hi, I've been using boost::program_options but I have some questions about it. First: to catch errors that the users makes when specifying command-line options (eg I declared an option to be integer-only but the user specified a string), I surrounded the call to store() by a try/catch block: try { boost::program_options::store( boost::program_options::command_line_parser(argc, argv). options(desc).positional(p).run(), vm); } catch (boost::program_options::invalid_option_value e) { } But now how do I give a meaningfull error message? The what() function of invalid_option_value is private, what other options do I have? Secondly, is there a mechanism to check the relation between options? I have a number of options: -a, -m and -d for add, modify and delete respectively; I want only one of them to be allowed at the same time. Also, when the -a option is specified, the -t and -r options are valid, and only then. Do I have to check all of that manually? Thanks. cheers, roel