at
Syntax:
#include <boost/bit_logic/bit_vector.hpp> 
bit_handle at ( size_type num ) ; 
bool at ( size_type num ) const ;

The at() does a checked range lookup. It is intended to be safer than operator[], since it will throw an exception. In this class however, all accesses are checked and therefore this is just redundant for Container like interfaces.

For example:

bit_vector<> v ( 3 ) ; 
cout << v.at(5) ;
Exceptions:
bit_logic::bit_out_of_bounds Index exceeds boundaries of container