Regex replace multiple new lines

Question

In C# how do i specify regex to replace multiple groups. For example i would like to replace more than one instance of either \r\n or \r\r with a environment newline. I logically wrote this regex , but i know it is wrong. Please correct and explain how it works.

System.Text.RegularExpressions.Regex.Replace(task.Message, @"(\r\n){2,}(\r\r){2,}", System.Environment.NewLine);

Input text

Stackoverflow

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User Experience

Where each line may be separated either by \r\n or \r\r. Expected outcome after regex replace is below

Stackoverflow    
StackExchange    
User Experience

Answer 1

The point is that your regex matches sequences of \r\n (2 or more) and then 2 or more sequences of \r\r. You need

[\r\n]+

Or [\r\n]{2,} if you need to only match 2 or more occurrences of \r or \n.

If you need to exactly match 2 or more common line break types (\r\n in Windows, \n in Unix/Linux and \r on Mac OS), use

(?:\r?\n|\r){2,}