C# aus Textdatei lesen

        public static string Translate(string text)
        {
            var from = "abcdefghijklmnopqrstuvwxyz";
            var to =   "jkhinolmrspqvwtuzGbcJafgde";
            var ret = new StringBuilder();
            foreach (var l in text)
            {
                int index;
                for (index = 0; index <= from.Length; index++)
                    if (index == from.Length || from[index] == l)
                        break;
                ret.Append(index != from.Length ? to[index] : l);
            }
            return ret.ToString();
        }

public static string Translate(string text)
{
	var fromTo = new Dictionary<char, char>()
	{
		{'a', 'j'},
		{'b', 'k'},
		{'c', 'l'},
		//usw...
	};
	
	var ret = new StringBuilder();
	
	foreach (char l in text)
	{
		if (fromTo.ContainsKey(l))
		{
			ret.Append(fromTo[l]);
		}
	}
	
	return ret.ToString();
}

        public static string Translate(string text, bool includeUntranslateable = true)
        {
            var fromTo = new Dictionary<char, char>()
            {
                {'a', 'j'},
                {'b', 'k'},
                {'c', 'h'},
                {'d', 'i'},
                {'e', 'n'},
                {'f', 'o'},
                {'g', 'l'},
                {'h', 'm'},
                {'i', 'r'},
                {'j', 's'},
                {'k', 'p'},
                {'l', 'q'},
                {'m', 'v'},
                {'n', 'w'},
                {'o', 't'},
                {'p', 'u'},
                {'q', 'z'},
                {'r', 'G'},
                {'s', 'b'},
                {'t', 'c'},
                {'u', 'J'},
                {'v', 'a'},
                {'w', 'f'},
                {'x', 'g'},
                {'y', 'd'},
                {'z', 'e'},
            };
            var ret = new StringBuilder();
            foreach (var l in text)
                if (fromTo.ContainsKey(l))
                    ret.Append(fromTo[l]);
                else if (includeUntranslateable)
                    ret.Append(l);
            return ret.ToString();
        }
    }

        static void Main(string[] args)
        {
            var dict1 = DictionaryFromStrings(
                "abcdefghijklmnopqrstuvwxyz",
                "jkhinolmrspqvwtuzGbcJafgde"
            );

            var dict2 = DictionaryFromStrings(
                "abcdefg",
                "1234567"
            );

            var input = Console.ReadLine();
            Console.WriteLine("Dict1: " + Translate(dict1, input));
            Console.WriteLine("Dict2: " + Translate(dict2, input));

            Console.ReadKey();
        }

        public static Dictionary<char, char> DictionaryFromStrings(string from, string to)
        {
            var ret = new Dictionary<char, char>();
            for (int i = 0; i < from.Length; i++)
                ret.Add(from[i], to[i]);
            return ret;
        }

        public static string Translate(Dictionary<char, char> dictionary, string text, bool includeUntranslateable = true)
        {
            var ret = new StringBuilder();
            foreach (var l in text)
                if (dictionary.ContainsKey(l))
                    ret.Append(dictionary[l]);
                else if (includeUntranslateable)
                    ret.Append(l);
            return ret.ToString();
        }