Using Regex to replace special character

Question

I'm trying to get some code in c# to check the start or end of a string and see if it has "\r\n" in one of these locations and if it does I want these characters removed. I do not want to remove these characters if they are not at the start or end though.

ex:

string tempStringA = "\r\n123\r\n456\r\n";
string tempStringB = "\r\n123\r\n456";
string tempStringC = "123\r\n456\r\n";

tempStringA, tempStringB, and tempStringC would all become "123\r\n456"

I understand it so that the CRLF must only be removed if the string starts and ends with CRLF. If only one instance must be removed, you may use Regex.Replace(s, @"\A\r\n(.*)\r\n\z", RegexOptions.Singleline). A non-regex way is still preferred: if (s.EndsWith("\r\n") && s.StartsWith("\r\n")) s = s.Substring(1, s.Length-2) — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Dec 7, 2016 at 21:54
@KGreve I revisited your question to see if I got chosen for the answer. I see you have added two more strings as examples that weren't there when I answered. I checked both of the new strings and they still have the \r\n removed with my answer. Is there some issue you're having with the answer? — Blake Thingstad
– Blake Thingstad, Commented Dec 7, 2016 at 22:21

garyh · Accepted Answer · 2016-12-07 21:43:44Z

1

var str1 = "\r\n123\r\n456\r\n";
var str2 = Regex.Replace(str1, @"^\r\n|\r\n$", "");

This just removes the \r\n at the start and end of the string

answered Dec 7, 2016 at 21:43

garyh

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Blake Thingstad · Accepted Answer · 2016-12-07 22:39:39Z

1

string str = @"\r\n123\r\n456\r\n";
str = Regex.Replace(str, @"^(\r\n)+|(\r\n)+$", "");

This works for your example and also works for "\r\n\r\n123\r\n456\r\n\r\n" if there are ever times where there is more than one of those characters.

Edit: Also works for "\r\n123\r\n456" and "123\r\n456\r\n"

edited Dec 7, 2016 at 22:39

answered Dec 7, 2016 at 21:41

Blake Thingstad

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2 Comments

KGreve Over a year ago

This works if you only use one \\ not with both str = Regex.Replace(str, @"^(\r\n)+|(\r\n)+$", "");

Blake Thingstad Over a year ago

@KGreve Oh good catch! I didn't actually try it out in C#, just an online regex tester, sorry about that. I edited the answer, which apparently removes it as marked as "correct".

Josiah · Accepted Answer · 2016-12-07 21:28:37Z

0

This is not regex, but regex might be overkill here.

string.Join( "\r\n", "\r\n123\r\n456\r\n".Split(new string[]{"\r\n"}, StringSplitOptions.RemoveEmptyEntries))

edited Dec 7, 2016 at 21:28

answered Dec 7, 2016 at 21:15

Josiah

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