using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var source = "The quick brown fox jumps over the lazy dog.";

        foreach(var chars in source.Chunk(5))

        {

            Console.WriteLine(new string(chars.ToArray()));

        }

    }

}

​

public static class ChunkHelper {

    public static IEnumerable<IEnumerable<T>> Chunk<T>(this IEnumerable<T> values, int chunkSize)

    {

        var e = values.GetEnumerator();

        while (e.MoveNext())

        {

            yield return innerChunk(e, chunkSize);

        }

    }

​

    private static IEnumerable<T> innerChunk<T>(IEnumerator<T> e, int chunkSize)

    {

        yield return e.Current;

​

        int i = 1; 

        while(i++ < chunkSize && e.MoveNext()) 

        {

            yield return e.Current;

        }

    }

}