PHP preg_replace matching two newline characters

Question

This seems a really simple exercise but It's just not working out for me.

I have a text document, and felt an easy way to HTMLify it is to use a quick regex to translate 2 newlines into a </p><p> , this is simple enough for what I need.

So; my regex:

\n\h*\n+
/** This matches the newline, 
    then any number (zero or more) whitespace 
    and then a second new line. **/

This works in regex101.com where I usually trial out my regexes. But in my PHP it's not working;

$text = trim($_POST['text']);
$text = strip_tags($_POST['text']);

/*** Find new Paragraphs ***/
$text = preg_replace("/\n\h*\n/","</p>\n<p>",$text);
$text = "<p>".$text."</p>";

My input:

30th Sep 16

Day 176 has seen more golf balls struck with growing frustration as I try
to train the brain, a short swim, and a dawning realisation which has led
to probably the biggest question that I have ever posed.

But my output on PHP is:

<p>30th Sep 16

Day 176 has seen more golf balls struck with growing frustration as I try
to train the brain, a short swim, and a dawning realisation which has led
to probably the biggest question that I have ever posed.</p>

Adding a $count var to the preg_replace returns zero, the match is not being found.

Expected output:

<p>30th Sep 16 </p>
 <p>Day 176 has seen more golf balls struck with growing frustration as I try
to train the brain, a short swim, and a dawning realisation which has led
to probably the biggest question that I have ever posed.</p>

What am I missing? I'm sure it's simple but I can't see why it works on a site but not on my extremely simple script :-/

I have also tried substituting \n for PHP_EOL and various other permutations of the code, to no success.

@bobblebubble yes, \R works. cheers, stick it in an answer :) — Mm-Art-In
– Mm-Art-In, Commented Feb 3, 2017 at 22:12
(incidentally I was searching earlier for a special character for newline characters but didn't find \R ... I knew the cause of this problem was something silly..... ) — Mm-Art-In
– Mm-Art-In, Commented Feb 3, 2017 at 22:13
@dan08 that's just global so it doesn't stop after the first match, habit for working with repeating matches. doesn't apply as preg_replace does that automatically — Mm-Art-In
– Mm-Art-In, Commented Feb 3, 2017 at 22:15

bobble bubble · Accepted Answer · 2017-02-03 22:29:59Z

1

Could be that you have \r\n line breaks. Try escape sequence \R for any linebreak sequence.

\R\h*\R+

See demo at regex101 or PHP Demo at eval.in

edited Feb 3, 2017 at 22:29

answered Feb 3, 2017 at 22:14

bobble bubble

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