Today I need to convert between string and hexadecimal in C#...

         public string StrToHex(string plainText)
        {
            char[] charArray = plainText.ToCharArray();
            StringBuilder sb = new StringBuilder();
            int num;
            string hex;
            for (int i = 0; i < charArray.Length; i++)
            {
                if (i > 0)
                {
                    sb.Append("-");
                }
                num = Convert.ToInt32(charArray[i]);
                hex = num.ToString("x");
                sb.Append(hex);
            }
             return sb.ToString();
        }

 ===========

         public string HexToStr(string hexaText)
        {
           string[] strArray = hexaText.Split(new char[] { '-' });
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < strArray.Length; ++i)
            {
                sb.Append((char)Convert.ToInt32(strArray[i], 16));
            }
            return sb.ToString();
        }

 ============ 

Implementation as

string str = "TestString";
string hexStr = StrToHex(str);   // => 54-65-73-74-53-74-72-69-6e-67
str = HexToStr(hexStr); // => TestString