Understanding C# IEnumerable and IEnumerator

Anything that you can iterate over in .NET implements IEnumerable

Photo by Kelly Sikkema on Unsplash

Introduction

As two of the very old programming concepts that are implemented in most languages nowadays, this guide helps you have a better understanding of the generic IEnumberable and IEnumberator interfaces.

Background

What Is Iterator Design Pattern

Gof definiton:

Provides a way to traverse the elements of an aggregate object without exposing the underlying representation.

An aggregate object can be:

• a data structure
• a collection
• a list
• a sequence of things of the same type

Some of the requirements when iterating the elements in real world might include:

1. Traverse in different ways, like forwards, backwards, pre-order or in-order etc
2. Keep track of the above traversal ways on the same collection at once
3. Traverse different types of aggregate object by using the same way