[Boost-users] [program_options] Using multitokens

In the example documentation a multitoken is used for strings as follows: ("email", boost::program_options::valuevaluestd::string()->multitoken(), "email to send to") This means the command line can have the following option. --email beadle@mars beadle2@mars I'm trying to use the multitoken with an unsigned long as follows: ("sending,s", boost::program_options::value<unsigned long>()->multitoken(), "Distination node address and port number to transmit data.") The command option I would like to use is: -s 23 6543 When trying to do this the following error occurs. Unhandled exception: in option 'sending': multiple values not allowed How do I correctly define a multitoken and then how do I retrieve the different values? Ryan