partitions an array of words into groups according to the first letter of each word.

   
 
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

public class MainClass {
    public static void Main() {

        string[] words = { "b", "c", "a", "ba", "ae", "ch" };

        var wordGroups =
            from w in words
            group w by w[0] into g
            select new { FirstLetter = g.Key, Words = g };

        foreach (var g in wordGroups) {
            Console.WriteLine("Words that start with the letter '{0}':", g.FirstLetter);
            foreach (var w in g.Words) {
                Console.WriteLine(w);
            }
        }
    }
}