private string Encrypt(EncryptedWord game)
        {
            string target;                      // the word need to be encrypted
            string targetAfterEncrypted;        // the word after encrypted
            int    invalidationWordCount;       // the number of invalid word

            invalidationWordCount = 0;
            targetAfterEncrypted  = "";
            target = GetRandomWord();

            if (CheckInputLengthValidation(target))
            {
                bool flag = true;
                for (int i = 0; i < target.Length; i++)
                {
                    char letter = target[i];
                    int  letterTransferToNum = (int)letter;
                    if (!CheckInputValidation(letterTransferToNum))
                    {
                        flag = false;
                    }
                }
                if (flag)
                {
                    targetAfterEncrypted = game.StartEncryptWord(target);
                }
                else
                {
                    if (invalidationWordCount < puzzle.Length)
                    {
                        invalidationWordCount++;
                        GetRandomWord();
                    }
                    else
                    {
                    }
                }
            }
            else
            {
                if (invalidationWordCount < puzzle.Length)
                {
                    invalidationWordCount++;
                    GetRandomWord();
                }
                else
                {
                    Console.Write("There is no valid word any more!");
                }
            }
            return(targetAfterEncrypted);
        }
        EncryptedWord game;                         // game

        public Driver()
        {
            encrytedWord = "";
            game         = new EncryptedWord();
        }