C# Iterators: Simplifying Collection Traversal

Learn how to use iterators in C# to efficiently traverse collections (arrays, lists). This tutorial explains the `yield return` statement, demonstrates creating custom iterators, and highlights their benefits for cleaner, more readable, and maintainable code when working with sequential data.

Understanding and Using Iterators in C#

Introduction

In C#, an iterator is a method that allows you to traverse the elements of a collection (like an array or list) one at a time. It uses the yield return statement to return each element, remembering its position for the next iteration. Iterators simplify working with collections and improve code readability.

Key Features of Iterators

• yield return: This statement returns a single element and pauses execution, remembering its place. The next call to the iterator resumes from where it left off.
• yield break: This statement stops the iteration.
• Return Types: An iterator method typically returns IEnumerable<T> or IEnumerator<T>.

Example 1: Iterating Through an Array

This example shows how to create an iterator that returns elements from an integer array.

using System;
using System.Collections.Generic;

namespace CSharpFeatures {
    class IteratorExample {
        public static IEnumerable<string> GetArray() {
            int[] arr = new int[] { 5, 8, 6, 9, 1 };
            foreach (var element in arr) {
                yield return element.ToString();
            }
        }

        public static void Main(string[] args) {
            IEnumerable<string> elements = GetArray();
            foreach (var element in elements) {
                Console.WriteLine(element);
            }
        }
    }
}

5
8
6
9
1
        

Explanation Example 1

GetArray() is the iterator. Each yield return pauses execution and returns a string representation of the current array element. The Main method iterates through the results.

Example 2: Iterating Through a List

This example demonstrates an iterator for a list of strings.

using System;
using System.Collections.Generic;

namespace CSharpFeatures {
    class IteratorExample {
        public static IEnumerable<string> GetList() {
            List<string> list = new List<string>();
            list.Add("Rohan");
            list.Add("Peter");
            list.Add("Irfan");
            list.Add("Sohan");
            foreach (var element in list) {
                yield return element;
            }
        }

        public static void Main(string[] args) {
            IEnumerable<string> elements = GetList();
            foreach (var element in elements) {
                Console.WriteLine(element);
            }
        }
    }
}

Rohan
Peter
Irfan
Sohan
        

Explanation Example 2

Similar to Example 1, but this iterator works with a list. The yield return statement efficiently returns each list element one at a time.

Conclusion

Iterators provide a clean and efficient way to process collections in C#. The yield return mechanism makes it easy to manage the iteration process and improves code readability.