C# 判断是不是合法的16进制字符串

方法一：用正则表达式判断，代码如下：

public const string PATTERN = @"([^A-Fa-f0-9]|\s+?)+";
        /// <summary>
        /// 判断十六进制字符串hex是否正确
        /// </summary>
        /// <param name="hex">十六进制字符串</param>
        /// <returns>true：不正确，false：正确</returns>
        public bool IsIllegalHexadecimal(string hex)
        {
            return System.Text.RegularExpressions.Regex.IsMatch(hex, PATTERN);
        }

　线性遍历输入的十六进制字符串中是否包含非十六进制字符，代码如下：方法二：

public IList<char> HexSet = new List<char>() 
       { '0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F','a','b','c','d','e','f' };       
       /// <summary>
       /// 判断十六进制字符串hex是否正确
       /// </summary>
       /// <param name="hex">十六进制字符串</param>
       /// <returns>true：不正确，false：正确</returns>
       public bool IsIllegalHexadecimal(string hex)
       {
           foreach (char item in hex)
           {
               if (!HexSet.Contains<char>(item))
                   return true;
           }
           return false;
       }

通过调用上述方法就可以清楚的知道输入的十六进制字符是否正确，然后为程序的下一个工作提供条件。

还有一种方法性能比较慢就放到文章最后面了

/// <summary>
        /// 判断是否为合法的16进制字符串
        /// </summary>
        /// <param name="hexString"></param>
        /// <returns></returns>
        public bool IsHexadecimal(string hexString)
        {
            try
            {
                hexString = hexString.Replace(" ", "").Replace("\r", "").Replace("\n", "");
                if ((hexString.Length % 2) != 0)
                    hexString += " ";
                byte[] returnBytes = new byte[hexString.Length / 2];
                for (int i = 0; i < returnBytes.Length; i++)
                    returnBytes[i] = Convert.ToByte(hexString.Substring(i * 2, 2), 16);
            }
            catch
            {
                return false;
            }
            return true;
        }
        #endregion