gistfile1.cs

static void Main(string[] args)
        {
            string pattern = @"^\((0*([0-9]{1,2}|1[0-9]{2}|2[0-4][0-9]|25[0-5]),){2}0*([0-9]{1,2}|1[0-9]{2}|2[0-4][0-9]|25[0-5])\)$";
            string input1 = @"(255,254,255)";
            string input2 = @"my color is (255,254,255) in rgb";

            input1 = Regex.Replace(input1, pattern, "MY_COLOR", RegexOptions.IgnoreCase);
            input2 = Regex.Replace(input2, pattern, "MY_COLOR", RegexOptions.IgnoreCase);
            Console.WriteLine(input1); // Result: "MY_COLOR"
            Console.WriteLine(input2); // Result: "my color is (255,254,255) in rgb"

            // I want to get : "my color is MY_COLOR in rgb"
        }

string pattern = @"((0_([0-9]{1,2}|1[0-9]{2}|2[0-4][0-9]|25[0-5]),){2}0_([0-9]{1,2}|1[0-9]{2}|2[0-4][0-9]|25[0-5]))";