using System;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using System.Net;

public class TaskParallelExample

{

    public static void Main()

    {

        // Retrieve Darwin's "Origin of the Species" from Gutenberg.org.

        string[] words = CreateWordArray(@"http://www.gutenberg.org/files/2009/2009.txt");

        #region ParallelTasks

        // Perform three tasks in parallel on the source array.

        Parallel.Invoke(() =>

                        {

                            Console.WriteLine("Begin first task...");

                            GetLongestWord(words);

                        },  // close first Action

​

                        () =>

                        {

                            Console.WriteLine("Begin second task...");

                            GetMostCommonWords(words);

                        }, //close second Action

​

                        () =>

                        {

                            Console.WriteLine("Begin third task...");

                            GetCountForWord(words, "species");

                        } //close third Action

                      ); //close parallel.invoke    

​

        Console.WriteLine("Returned from Parallel.Invoke");

        Console.WriteLine("Press any key to exit");

        Console.ReadLine();

        #endregion  

    }   

    #region HelperMethods

    private static string GetLongestWord(string[] words)

    {

        var longestWord = (from w in words

                           orderby w.Length descending

                           select w).First();

        Console.WriteLine("Task 1 -- The longest word is {0}", longestWord);

        return longestWord; 

    }

    private static void GetMostCommonWords(string[] words)

    {

        var frequencyOrder = (from w in words

                              where w.Length > 6

                              group w by w into g

                              orderby g.Count() descending

                              select g.Key);

        var commonWords = frequencyOrder.Take(10);

        StringBuilder sb = new StringBuilder();

        sb.AppendLine("Task 2 -- The most common words are:");      

        foreach (var v in commonWords)

        {

            sb.AppendLine("  " + v);

        }

        Console.WriteLine(sb.ToString());   

    }

    private static void GetCountForWord(string[] words, string term)

    {

        var findWord = from word in words

                       where word.ToUpper().Contains(term.ToUpper())

                       select word;

​

        Console.WriteLine(@"Task 3 -- The word ""{0}"" occurs {1} times.", term, findWord.Count());

    }

    // An http request performed synchronously for simplicity.

    static string[] CreateWordArray(string uri)

    {

        Console.WriteLine("Retrieving from {0}", uri);

        // Download a web page the easy way.

        string s = new WebClient().DownloadString(uri);

        // Separate string into an array of words, removing some common punctuation.

        return s.Split(

            new char[] { ' ', '\u000A', ',', '.', ';', ':', '-', '_', '/' },

            StringSplitOptions.RemoveEmptyEntries);

    }

    #endregion

}