[Cs3] lower_bound and upper_bound

[Mikhail Nesterenko]

CS3 students,

For maps, multi_maps, sets:  lower_bound and upper_bound
operate as follows. 

   lower_bound(key) returns the iterator to the first element that is
      not smaller than key. That is, it returns end() if the element
      with this key is missing from container

   upper_bound(key) returns the iterator to the first element that is
      greater than the key. Again, returns end() if key is missing


lower_bound() and upper_bound are not defined for hashes.

Note also that there is std::lower_bound() and std:upper_bound()
algorithms that can be applied to any half-open range of iterators
and, therefore, can be used for non-associative containers such as
vectors. 

Thanks,
-- 
Mikhail