C#-Code

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

namespace CountWords {
  class Program {
    static string
      filename = "",
      text = "";

    readonly static char[] alphabet = GetLowerAlphabet();

    static void Main() {
      do {
        Console.Write("Datei>");
        filename = Console.ReadLine();
      } while(!File.Exists(filename));

      //Text-Datei ist nicht ASCII-Kodiert.
      //Ist auch Unsinn da ASCII keine Umlaute beinhaltet, auf welche aber explizit eingegangen werden soll.
      text = File.ReadAllText(filename, Encoding.UTF7).ToLower();

      char[] separators = text.Where(x => !alphabet.Contains(x)).Distinct().ToArray();
      string[] words = text.Split(separators, StringSplitOptions.RemoveEmptyEntries);

      Dictionary<int, int> WordLengths = CountWordLength(words);

      foreach(var WordLength in WordLengths) {
        Console.WriteLine("{0}: {1}", WordLength.Key, WordLength.Value);
      }
      Console.WriteLine("Gesamt: {0}", WordLengths.Sum(x => x.Value));

      Console.ReadKey(true);
    }

    static char[] GetLowerAlphabet() {
      List<char> AllTheLetters = new List<char>() {
        'ä', 'ö', 'ü', 
      };

      for(char letter = 'a'; letter <= 'z'; letter++) {
        AllTheLetters.Add(letter);
      }

      return AllTheLetters.ToArray();
    }

    static Dictionary<int, int> CountWordLength(IEnumerable<string> words) {
      Dictionary<int, int> AllTheLengths = new Dictionary<int, int>();

      foreach(string word in words) {
        if(!AllTheLengths.ContainsKey(word.Length)) {
          AllTheLengths.Add(word.Length, 1);
        } else {
          AllTheLengths[word.Length]++;
        }
      }

      return AllTheLengths.OrderBy(x => x.Key).ToDictionary(x => x.Key, x => x.Value);
    }
  }
}

C#-Code

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using Word = Microsoft.Office.Interop.Word;

namespace ConsoleCountWords
{
    static class Program
    {
        const string allChars = "abcdefghijklmnopqrstuvwxyzäöüß";

        [STAThread]
        static void Main(string[] args)
        {
            OpenFileDialog ofd = new OpenFileDialog();
            ofd.Filter = "Textdateien (*.txt)|*.txt";
            if (ofd.ShowDialog() == DialogResult.OK)
            {
                string file = ofd.FileName;
                string text = File.ReadAllText(file, Encoding.ASCII);
                object missing = System.Reflection.Missing.Value;

                Word.Application app = new Word.Application();
                Word.Document document = app.Documents.Add(ref missing, ref missing, ref missing, ref missing);
                document.Content.SetRange(0, 0);
                document.Content.Text = text;
                Dictionary<int, int> wordLength;
                int count = document.CountWords(out wordLength);

                if (count == 1)
                { Console.WriteLine("1 Wort gezählt"); }
                else
                { Console.WriteLine("{0} Wörter gezählt", count); }

                foreach (var item in wordLength.OrderBy(a => a.Key))
                {
                    if (item.Value == 1)
                    {
                        Console.WriteLine("1 Wort der Länge {0} gezählt", item.Key);
                    }
                    else
                    {
                        Console.WriteLine("{0} Wörter der Länge {1} gezählt", item.Value, item.Key);
                    }
                }

                document.Close(Word.WdSaveOptions.wdDoNotSaveChanges);
                app.Quit();

                Console.ReadLine();
            }
        }

        static int CountWords(this Word.Document doc, out Dictionary<int, int> wordLength)
        {
            int c = 0;
            wordLength = new Dictionary<int, int>();
            for (int i = 1; i <= doc.Words.Count; i++)
            {
                string word = doc.Words[i].Text.ToLower();
                if (!allChars.Contains(word.Last()))
                { word = word.Substring(0, word.Length - 1); }
                if (word.All(a => allChars.Contains(a)) && word.Length > 0)
                {
                    c++;
                    if (wordLength.ContainsKey(word.Length))
                    { wordLength[word.Length]++; }
                    else
                    {
                        wordLength.Add(word.Length, 1);
                    }
                }
            }
            return c;
        }
    }
}

C#-Code

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

namespace ascii {
    class Program    {
        public static void Main()   {

            char[] all_ok = "abcdefghijklmnopqrstuvwxyzäöüABCDEFGHIJKLMNOPQRSTUVWXYZÄÖÜß".ToCharArray();
            char[] trenner = " .!?,;<>()[]{}§$%&=+-*/:#|_~\"\'@".ToCharArray();

            string path = "Bibelausgabe_Martin_Luther_1912_als_ASCII_Datei.txt";
            Console.WriteLine("source: " + path + Environment.NewLine);

            int counter_lines = 0, counter_words = 0, counter_words_ok = 0;
            
            Dictionary<String, Int32> dictionary = new Dictionary<string, int>();
            int max_wortlaenge = 0; 
            string line;

            System.IO.StreamReader file = new System.IO.StreamReader(path, Encoding.Default);

            while ((line = file.ReadLine()) != null)  {

                String[] words_in_line = line.Split(trenner, StringSplitOptions.RemoveEmptyEntries);

                counter_words += words_in_line.Length;

                for (var i = 0; i < words_in_line.Length; i++ )  {

                    char[] wordchars = words_in_line[i].ToCharArray();
                    Boolean bo_ok = true;

                    for(var j = 0; j < wordchars.Length; j++)
                        if (!(all_ok.Contains(wordchars[j])))
                            bo_ok = false;

                    if (bo_ok)  {

                        counter_words_ok++;
                        String erg = words_in_line[i].ToLower();

                        if (erg.Length > max_wortlaenge)
                            max_wortlaenge = erg.Length;

                        if (dictionary.ContainsKey(erg))    {
                            int value = dictionary[erg];
                            value++;
                            dictionary[erg] = value;
                        }
                        else
                            dictionary.Add(erg, 1);                       
                    }
                }
                counter_lines++;
            }

            file.Close();

            Console.WriteLine("there were {0:n0} lines, {1:n0} words and {2:n0} words_ok", 
                counter_lines, counter_words, counter_words_ok);
            Console.WriteLine();
            Console.WriteLine("different words: " + dictionary.Count.ToString() + ", longest word has " + 
                max_wortlaenge.ToString() + " chars");
            Console.WriteLine();

            int[] verteilung = new int[max_wortlaenge];

            foreach(String s in dictionary.Keys)
                verteilung[s.Length - 1] += 1;

            Console.WriteLine("distribution" + Environment.NewLine);
            Console.WriteLine(verteilung.ToMyString());
            Console.WriteLine("ready");
            Console.ReadKey();
        }
    }

    static class myExtensions    {
        public static string ToMyString(this int[] b)        {
            String erg = String.Empty;
            for (var i = 0; i < b.Length; i++)
                erg += (i + 1).ToString("00") + ": " + b[i].ToString() + Environment.NewLine;
            return erg;
        }
    }
}