C# Regex: Get group names?

myRegex.GetGroupNames()

Seems to r开发者_JAVA技巧eturn the numbered groups as well... how do I get only the named ones?

A solution using the actual Match object would be fine as well.

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Does using the RegexOptions.ExplicitCapture option when creating the regex do what you want ? e.g.

Regex theRegex = new Regex(@"\b(?<word>\w+)\b", RegexOptions.ExplicitCapture);

From MSDN:

Specifies that the only valid captures are explicitly named or numbered groups of the form (?<name>...). This allows unnamed parentheses to act as noncapturing groups without the syntactic clumsiness of the expression (?:...).

So you won't need to worry about whether users of your API may or may not use non-capturing groups if this option is set.

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See the other comments/answers about using (?:) and/or sticking with "one style". Here is my best approach that tries to directly solve the question:

var named = regex.GetGroupNames().Where(x => !Regex.IsMatch(x, "^\\d+$"));

However, this will fail for regular expressions like (?<42>...).

Happy coding.

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public string[] GetGroupNames(Regex re)
{
    var groupNames = re.GetGroupNames();
    var groupNumbers = re.GetGroupNumbers();

    Contract.Assert(groupNames.Length == groupNumbers.Length);

    return Enumerable.Range(0, groupNames.Length)
        .Where(i => groupNames[i] != groupNumbers[i].ToString())
        .Select(i => groupNames[i])
        .ToArray();
}

Actually, this will still fail when the group name and number happen to be the same :\ But it will succeed even when the group name is a number, as long as the number is not the same as its index.