Regex (C#): Replace \n with \r\n

Question

How can I replace lone instances of \n with \r\n (LF alone with CRLF) using a regular expression in C#?

Sorry if it's a stupid question, I'm new to Regex.

I know to do it using plan String.Replace, like:

myStr.Replace("\n", "\r\n"); myStr.Replace("\r\r\n", "\r\n"); 

However, this is inelegant, and would destroy any "\r+\r\n" already in the text (although they are not likely to exist).

Answer 1

It might be faster if you use this.

(?<!\r)\n 

It basically looks for any \n that is not preceded by a \r. This would most likely be faster, because in the other case, almost every letter matches [^\r], so it would capture that, and then look for the \n after that. In the example I gave, it would only stop when it found a \n, and them look before that to see if it found \r