Question

why regex return multi value for the match?

See the following code, it should only return one result. why there are two?

e.g 
Match m = Regex.Match("[Red] #,0.00 \"Ex\"", @"^\[(RED|GREEN|ORANGE)\]", RegexOptions.IgnoreCase);

            if (m.Success)
            {
                Console.WriteLine(m.Groups.Count);    
                Console.WriteLine(m.Groups[0].Value);
                Console.WriteLine(m.Groups[1].Value);
            }
            else
                Console.WriteLine("No match");

========Result===============
2
[Red]
Red
Press any key to continue . . .

Answer 1

There is a single match m, which has a single capturing group. m.Groups[0] is always the entire match. m.Groups[1] is the first capture, etc..

If you want to see all matches, you can do this:

foreach (Match m in regex.Matches (input))
   Console.WriteLine (m.Value);