Given a program that uses an iterator, the task is to find the type of iterator used.
Input : vector.begin()
Output : Random_Access Iterator
Input : list.begin()
Output : Bidirectional Iterator
There are namely five types of iterators present in the C++ Standard Library which are mentioned below:
- Forward Iterator in C++
- Bidirectional_Iterators in C++
- Input iterators in C++
- Output iterator in C++
- Random_access iterators in C++
- Iterator type can be checked by using typeid. typeid is a C++ language operator which returns type identification information at run time. It basically returns a type_info object, which is equality-comparable with other type_info objects.
- Along with it use iterator traits. Traits class defines properties of iterators. Standard algorithms determine certain properties of the iterators passed to them and the range they represent by using the members of the corresponding iterator_traits instantiation.
- Also a iterator category is passed which defines the iterator category the iterator belongs to.
There are five type of tags namely: input_iterator_tag, output_iterator_tag, forward_iterator_tag, bidirectional_iterator_tag, random_access_iterator_tag.
- typename is used along with it to provide a type to the iterator during instanitation.
- Now if the iterator category of the input iterator matches the existing iterator categories the result is displayed.
Time-Complexity: O(1) to find the iterator type