Question

What kind of iterators (forward, bidirectional, or random access) does the stack template adapter class have?

Short answer

Answer: The stack adapter class does not provide iterators directly due to its LIFO policy. Therefore, it does not have specific iterator types like forward, bidirectional, or random access iterators. However, you can access the iterators of the underlying container (such as deque) if needed, but this would violate the LIFO policy of the stack data structure.

Step-by-step solution

Understand Stack Container Adapter

Stack is a container adapter that uses another container class as its underlying container. It follows the Last-In-First-Out (LIFO) policy, meaning that elements are inserted and removed only at the top of the stack. The default container used by stack is deque, but it can also use other containers like list or vector.

Checking Deque Iterator Types

The deque container provides random access iterators. That means, with deque, the iterators have the ability to access, add, and remove elements directly at any position within the container.

Checking if Stack Supports Iterators

Stack, as an adapter, does not expose iterators directly. This is due to its LIFO policy, which restricts inserting and removing elements only from the top of the stack. Even though the underlying containers (like deque) support iterators, the stack class itself does not provide this functionality to retain its LIFO property.

Stack Iterator Types

Since stack does not provide iterators directly, it does not have any specific iterator types like forward, bidirectional, or random access iterators. However, if you need iterator-like functionality in a customized stack, you can use the underlying container's iterators. For example, if you use a deque as the underlying container, you can access its random access iterators directly through the deque, but keep in mind that this will violate the LIFO policy of the stack data structure.