String Extension Method: IsGuid()

I wrote an extension method for the string type. With this method you can check if an string is an Guid. The method returns a Bool.

[code:c#]

public static class StringExtensions
{
  public static bool IsGuid(this string input)
  {
    Regex isGuid = new Regex(@"^({){0,1}[0-9a-fA-F]{8}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{4}-[0-9a-fA-F]{12}(}){0,1}$", RegexOptions.Compiled);
    bool isValid = false;
    if (input != null)
    {
      if (isGuid.IsMatch(input))
      {
        isValid = true;
      }
    }
  return isValid;
  }
}

[/code]

If you're wondering I didn't wrote the Regex myself :-) (but it works)

This brute-force method is mutch faster (thanks to Arjan and Tag for the comments):

[code:c#]

public static bool IsGuid(this string input)
{
try
{
new Guid(input);
return true;
}
catch (ArgumentNullException) {}
catch (FormatException) {}
catch (OverflowException) {}
return false;
}

[/code]

A good example how extension methods can make some things easier. 

Hope it helps!