Regular Expression to match cross platform newline characters

Question

My program can accept data that has newline characters of \n, \r\n or \r (eg Unix, PC or Mac styles)

What is the best way to construct a regular expression that will match whatever the encoding is?

Alternatively, I could use universal_newline support on input, but now I'm interested to see what the regex would be.

Just note, `\r` is the _old_ Mac style (and by "old" I mean "OS 9 and before"). Any Mac running OS X (a.k.a. made after 1999) is going to use `\n` like any other Unix. — Chris Lutz, Aug 26 '09 at 01:07
When is it useful to match newlines vs. using `'$'` to match the end of the line ? — tonfa, Aug 26 '09 at 01:10
@too much php But wouldn't str.splitlines() works just as well? — tonfa, Aug 26 '09 at 01:21
@tonfa: OK so it's not needed often, but it's good to know for other languages that don't have convenient functions like `splitlines()`. — too much php, Aug 26 '09 at 01:25

score 96 · Accepted Answer · answered Aug 26 '09 at 01:02

96

The regex I use when I want to be precise is "\r\n?|\n".

When I'm not concerned about consistency or empty lines, I use "[\r\n]+", I imagine it makes my programs somewhere in the order of 0.2% faster.

answered Aug 26 '09 at 01:02

too much php

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Usually when I'm not concerned about newlines, I'm also not concerned about spaces either. – Brad Gilbert Aug 30 '09 at 00:12
What makes your programs faster? – sehe Sep 13 '17 at 06:29

Diego V · Answer 2 · 2017-11-01T10:17:45.203

10

The pattern can be simplified to \r?\n for a little performance gain, as you probably don't have to deal with the old Mac style (OS 9 is unsupported since February 2002).

edited Nov 01 '17 at 10:17

answered Aug 18 '16 at 15:40

Diego V

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Regular Expression to match cross platform newline characters

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