boost program options - how to automatically store the value of a simple flag into a variable? -

the boost option parser allows 1 assign variable store option value, instead of using so_long["typing"].as<bool>() way:

bool flag_value; entries.add_options() ("flag", value<bool>(&flag_value), "a simple flag value"); ...... cout<<"flag value is: "<<flag_value<<endl; 

however, above option declaration not create simple flag option. requires enter value (--flag true|false|on|off|yes|no|1|0), not want.

so, there way store result inside boolean value, , still keep option simple flag?

to have option no value (passing means set true) should create this:

options_description desc; desc.add_options()     ("help", "produce message") 

to use notifier such option can use following type semantics:

boost::program_options::bool_switch() 

it can have true or false values , no value can explicitly taken option command line. if option passed value true. if not passed - value false.