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.

Vasodilator

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. – Marvelmarvella

When is it useful to match newlines vs. using '$' to match the end of the line ? – Triceratops

@tonfa: When splitting a file into lines via regex. – Meister

@too much php But wouldn't str.splitlines() works just as well? – Triceratops

@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(). – Meister

Answer 1

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.

Meister

Usually when I'm not concerned about newlines, I'm also not concerned about spaces either. – Scattering

What makes your programs faster? – Seedbed

Answer 2

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).

Inordinate