#include <boost/bit_logic/bit_vector.hpp> 
bit_handle back ( ) ;
bool back ( ) const ; 

The back() function returns a bit_handle to the last bit of a bit_vector, the const method just returns the value.

For example:

bit_vector<> v (4) ; 
v = "1000";
cout << v.back() << endl ; 

This code would produce this output:

1

This code throws no exceptions.