ilIEnumerable

IEnumerable is a fundamental interface in the .NET Framework that represents a sequence of elements that can be enumerated. It is defined in the System.Collections namespace. The primary purpose of IEnumerable is to provide a standard way to iterate over a collection of items.

The IEnumerable interface has a single method, GetEnumerator(), which returns an IEnumerator object. The IEnumerator interface, in turn, provides methods to traverse the collection one element at a time. Specifically, it has a Current property to get the current element and a MoveNext() method to advance to the next element. The IEnumerator also has a Reset() method to move the enumerator back to its initial position, although this is less commonly used.

Implementing IEnumerable allows a class to be used in constructs like foreach loops, which are a convenient way to process each item in a collection. Many built-in .NET collection types, such as List<T>, Array, and Dictionary<TKey, TValue>, implement IEnumerable.

LINQ (Language Integrated Query) heavily relies on IEnumerable. Many LINQ extension methods operate on or return IEnumerable, making it a cornerstone of data manipulation and querying in C# and other .NET languages. It represents a "pull" model of data consumption, where the consumer requests elements as needed, rather than a "push" model where data is actively sent to the consumer. This lazy evaluation capability is a key benefit, especially for large datasets, as it avoids loading the entire collection into memory at once.