I'm a little fuzzy on what the difference between a "group" and a "capture" are when it comes to .NET's regular expression language. Consider the following C# code:
MatchCollection matches = Regex.Matches("{Q}", @"^\{([A-Z])\}$");
I expect this to result in a single capture for the letter 'Q', but if I print the properties of the returned MatchCollection, I see:
matches.Count: 1
matches[0].Value: {Q}
matches[0].Captures.Count: 1
matches[0].Captures[0].Value: {Q}
matches[0].Groups.Count: 2
matches[0].Groups[0].Value: {Q}
matches[0].Groups[0].Captures.Count: 1
matches[0].Groups[0].Captures[0].Value: {Q}
matches[0].Groups[1].Value: Q
matches[0].Groups[1].Captures.Count: 1
matches[0].Groups[1].Captures[0].Value: Q
What exactly is going on here? I understand that there's also a capture for the entire match, but how do the groups come in? And why doesn't matches[0].Captures include the capture for the letter 'Q'?