Regex question: Retrieve group names in code?

[Jeff Johnson [MVP: VB]]

[Pardon the crossposting, but it seemed appropriate given the lack of a
dedicated group]

Is there any way to retrieve the name of a capture group from the classes
provided in the RegularExpressi ons namespace? GroupCollection implements
ICollection and IEnumerable, not IDictionary, so there doesn't seem to be
any means to retrieve key values.

While I realize this isn't generally needed in a production scenario (you
normally KNOW what your groups are called), it is quite necessary if you're
building a general regular expression evaluation app (like The Regulator or
Regex Workbench).

In case I'm not being clear, consider the following example (error-trapping
and most braces omited for brevity--and in two languages to justify the
crosspost):

[You have a form with three text boxes, txtRegex, txtString, and txtOutput.
The user puts "(?<month>\d{1, 2})/(?<day>\d{1,2})/(?<year>\d{4})" into
txtRegex and "Today's date is 12/1/2004. Where has the year gone?" in
txtString and clicks the Evaluate button.]

-------VB--------
Private Sub btnEval_Click(B yVal sender As Object, ByVal e As
System.EventArg s) Handles btnEval.Click
Dim rgx As Regex, m As Match
rgx = New Regex(txtRegex. Text)
m = rgx.Match(txtSt ring.Text)
If m.Success Then
For Each g As Group In m.Groups
If g.Index <> 0 Then
' This is what I'd LIKE to do
txtOutput.Appen dText("Group '" & g.Name & "' = '" & g.Value
& "'" & Environment.New Line)
End If
Next
End If
End Sub
--------------------

--------C#--------
private void btnEval_Click(o bject sender, System.EventArg s e)
{
Regex rgx = new Regex(txtRegex. Text);
Match m = rgx.Match(txtSt ring.Text);
if (m.Success)
foreach (Group g in m.Groups)
if (g.Index != 0)
// This is what I'd LIKE to do
txtOutput.Appen dText("Group '" + g.Name + "' = '" + g.Value
+ "'\r\n");
}
--------------------

I would then like the output text box to contain:

Group 'month' = '12'
Group 'day' = '1'
Group 'year' = '2004'

(And pardon my C# if I made any syntax or style mistakes.)

[Lucas Tam]

"Jeff Johnson [MVP: VB]" <i.***@enough.s pam> wrote in news:usM8pp91EH A.4028
@TK2MSFTNGP15.p hx.gbl:

I would then like the output text box to contain:

Group 'month' = '12'
Group 'day' = '1'
Group 'year' = '2004'

You can use the method: GroupNameFromNu mber to retreive the group name.
To get the GroupNumber, you can just iterate through the group collection.

--
Lucas Tam (RE********@rog ers.com)
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