C# Regex capturing groups

Question

Trying to wrap my head around Regex capturing groups and having a little trouble.

I have some strings for which I want to capture groups for:

@msg=hello;name=test 1 // Groups: msg = hello, name = test, rest = 1 
@msg=hi 2 // Groups: msg = hello, name = null, rest = 2
@name=tt 3 // Groups: msg = null, name = tt, rest = 3

I have the following regex:

msg=(?P<msg>[^;]+)?.*name=(?P<name>[^;]+)?\s(?P<rest>.*)

Which works fine for the first row, but not the second or third. Any idea how I can make it work for them too? I tried putting some ()? around the capturing groups to no avail:

// Below gets me weird results
(msg=(?P<msg>[^;]+)?)?.*(name=(?P<name>[^;]+)?)?\s((?P<rest>.*))?

Thanks.

There's some great Regex testers out there that should be able to help you. Play around with regexr.com until you find what you're looking for, you can learn a lot while doing it :) — Ben Kolya Mansley
– Ben Kolya Mansley, Commented Sep 14, 2015 at 1:38

hwnd · Accepted Answer · 2015-09-14 07:01:58Z

1

You should use a more strict token rather than negation, using optional non-capturing groups:

@(?:msg=(?<msg>\w+);?)?(?:name=(?<name>\w+))?\s*(?<rest>.*)

Regex Demo

edited Sep 14, 2015 at 7:01

answered Sep 14, 2015 at 2:09

hwnd

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2 Comments

Sebastian Schumann Over a year ago

I'm very firm with Regex but I didn't see the construct (?P< for named groups in C# before. What's the difference between (?P<xxx> and (?<xxx>? Msdn doesn't know this pattern. Btw: This pattern doesn't work in C#. Are we really talking about C#?

hwnd Over a year ago

Sorry, it was intended to be reduced before but it saved the post with the original named group.

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