Iterator

Iterator Design Pattern C++ (under construction):

Problem:
Definition:

Provide a way to access the element sequentially.

objective/purpose:
Key Points:

• decouple algorithm and data structure.
• Need to transverse.
• Different way of transverse.
• New API like next or previous API
• provide uniform traverse.
• Without expose internal object.
• Std transverse protocol.
• access or traverse.
• generic programming (separate algorithm from data structure)
• Two hierarchy same like visitor.
• Iterator can transverse and access only but visitor can apply operation on it.
• Memento can be used into iterator to restore the previous state.
• It adds a new wrapper on container to provide the new API like next, previous.
• By adding wrapper, we are following OCP (open close principle).
• If we don’t want to use STL container in embedded device, we can create own container and can provide API with iterator pattern.
• dvantage:

Disadvantage:
Class Diagram:
Real Class Diagram Example:
Source code with real example:
Output: