判断是否是非法字符

 /// <summary>
        /// 判断是否是非法字符
        /// </summary>
        /// <param name="str">判断是字符</param>
        /// <returns></returns>
        protected static Boolean isLegalNumber(string str)
        {
            char[] charStr = str.ToLower().ToCharArray();
            if (charStr[0] == '0')
            {
                return false;
            }
            for (int i = 0; i < charStr.Length; i++)
            {
                int num = Convert.ToInt16(charStr[i]);
                if (!(num >= 48 && num <= 57))
                {
                    return false;
                }
            }
            return true;
        }