SOLID & Design Patterns Interview Question #44

What is the Iterator Pattern?

Structural, Creational & Behavioral Patterns Mid-Level Intermediate

Quick Interview Answer

The Iterator Pattern provides a way to traverse elements of a collection without exposing the collection's internal representation. The caller works through a traversal abstraction instead of managing storage details.

Detailed Explanation

C# implements this concept through IEnumerable<T>, IEnumerator<T>, foreach, and iterator methods using yield return.

Code Example

public IEnumerable<int> EvenNumbers(
    IEnumerable<int> source)
{
    foreach (var number in source)
        if (number % 2 == 0)
            yield return number;
}