C# Iterators

C# iterator is a method. It is used to iterate the elements of a collection, array or list. An iterator uses yield return statement to return each element at a time.

The iterator remembers the current location and in next iteration, it returns the next element.

The return type of an iterator can be IEnumerable<T> or IEnumerator<T>.

To stop iteration, we can use yield break statement.

C# Iterator Example 1

In this example, we are iterating array elements.

using System;
using System.Collections.Generic;
using System.Linq;
namespace CSharpFeatures
{
    class IteratorExample
    {
        public static IEnumerable<string> GetArray()
        {
            int[] arr = new int[] { 5,8,6,9,1 };
            // Iterating array elements and returning
            foreach (var element in arr)
            {
                yield return element.ToString(); // It returns elements after executing each iteration
            }
        }
        public static void Main(string[] args)
        {
            // Storing elements, returned from the iterator method GetArray()
            IEnumerable<string> elements = GetArray();
            foreach (var element in elements) // Iterating returned elements
            {
                Console.WriteLine(element);
            }
        }
    }
}

Output:

Iterator can also be used to iterate collection elements. In the following example, we are iterating list elements.

C# Iterator Example 2

using System;
using System.Collections.Generic;
using System.Linq;
namespace CSharpFeatures
{
    class IteratorExample
    {
        public static IEnumerable<string> GetList()
        {
            // List of string elements
            List<string> list = new List<string>();
            list.Add("Rohan"); // Adding elements
            list.Add("Peter");
            list.Add("Irfan");
            list.Add("Sohan");
            // Iterating and returing list elements
            foreach (var element in list)
            {
                yield return element; // It returns elements after executing each iteration
            }
        }
        public static void Main(string[] args)
        {
            // Storing elements, returned from the iterator method GetList()
            IEnumerable<string> elements = GetList();
            foreach (var element in elements) // Iterating returned elements
            {
                Console.WriteLine(element);
            }
        }
    }
}

Output: