#include <boost/bit_logic/bit_vector.hpp>
   bit_vector ( ) ; 
   bit_vector ( const bit_vector & c ) ;
   bit_vector ( size_type num, bool val = false ); 
   bit_vector ( input_iterator start, input_iterator end ) ; 
   ~bit_vector ( ) ; 

BlockT	Default : implementation-defined	Bit Storage type data word to be used for storing bit data
AllocT	Default: std::allocator<BlockT>	Allocator for BlockT data words.

The default bit_vector construct a 0 length bit_vector. The copy constructor duplicates the original size and contents of the copied vector

The sized constructor

For example:

 bit_vector<> simple (16); 
 cout << simple << endl ;

This code would produce this output:

 0000000000000000

Now creating a bit_vector with values defaulted to all 1's.

 bit_vector<> bv2 (16, true); 
 cout << simple << endl ;

This code would produce this output:

 1111111111111111