#include <boost/bit_logic/bit_array.hpp> 
   bit_vector <> extract ( std::size_t upper_bit_idx, std::size_t lower_bit_idx ) ; 

The extract function returns a bit_vector which is a copy of .

For example:

 bit_array<6> v ( ) ; 
 v = "110011" ; 
 cout << v.extract ( 3, 2 ) << endl ; 

This code produces the output:

 00

std::logic_error	Backwards ordering of range selection
bit_logic::bit_out_of_bounds	Index exceeds boundaries of container