How do I get the named groups in a regex

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I have the following list of regular expressions

C#

private List<Regex> _timeExtractionRegex = new List<Regex>()
        {
            new Regex(@"(?<hour>\d\d?):(?<minute>\d\d)\s?(?<meridiem>(a|p).?m)" , RegexOptions.IgnoreCase),
            new Regex(@"(?<hour>\d\d?)\s?(?<meridiem>(a|p).?m)" , RegexOptions.IgnoreCase),
            new Regex(@"(?<hour>\d\d?):(?<minute>\d\d)" , RegexOptions.IgnoreCase)
        }

The first one has named groups - hour, minute and meridiem.
The second one has named groups - hour and meridiem.

The problem is that this is being sent to me from a different source. How do i get all the names of the named capture groups ??

Posted 22-Oct-14 2:16am

rohith naik

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DamithSL · Accepted Answer · 2014-10-22T02:45:00

Quote:
How do i get all the names of the named capture groups ??

C#

int name;
var groupNames = _timeExtractionRegex.SelectMany(x=>x.GetGroupNames())
     .Where(n=>!int.TryParse(n, out name))
	 .Distinct().ToList();

Note that GetGroupNames method will return unnamed groups as numerical numbers like 0,1,2 so on, I have added where close to filter out those group names.

OriginalGriff · Accepted Answer · 2014-10-22T02:44:00

If you mean "how do I get teh match data by name?", that's easy:

C#

string inputText = "12:45";
Regex regex = new Regex(@"(?<hour>\d\d?):(?<minute>\d\d)\s?(?<meridiem>(a|p).?m)", RegexOptions.IgnoreCase);
Match m = regex.Match(inputText);
string hour = m.Groups["hour"].Value;

If you mean "how do I get the manes of the groups?", that's pretty simple too:

C#

Regex regex = new Regex(@"(?<hour>\d\d?):(?<minute>\d\d)\s?(?<meridiem>(a|p).?m)", RegexOptions.IgnoreCase);
string[] names = regex.GetGroupNames();

Do note that the GroupNames array will contain "0" and "1" for the two unnamed groups in your expression, as well as the names of the named ones.

How do I get the named groups in a regex

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