Replacing empty paragraph using preg_replace, whitespace not recognized

Question

I need to change this:

<p> </p>

Into this:

<p class="notmobile"> </p>

on a string. Seems simple, but the following don't work:

$filecontent  = preg_replace('/<p> <\/p>/', '<p class="notmobile"> </p>',   $filecontent);
$filecontent  = preg_replace('/^<p> <\/p>/', '<p class="notmobile"> </p>',  $filecontent);
$filecontent  = preg_replace('/<p>\s<\/p>/', '<p class="notmobile"> </p>',  $filecontent);
$filecontent  = preg_replace('/<p>\s+<\/p>/', '<p class="notmobile"> </p>', $filecontent);
$filecontent  = str_replace('<p> </p>', '<p class="notmobile"> </p>',   $filecontent);

To make sure I wasn't going crazy, I did a replace on xxx to turn it into yyy which worked just fine. I think the problem is my space isn't a normal space as the content is probably that windows character set iso-8859-1 or whatever it is (or it's got confused because we've converted that to utf-8 somewhere along the line..)

Copying and pasting the empty paragraph from chome/firefox didn't work either.

I'm a bit stuck :( Thanks for helping!

Update: Here's the base64_output, AwMD is a string of 0s which I used to mark the beginning of a string of p's as above.

AwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDAwMDA8L3A+DQo8cD7CoDwvcD4NCjxwPsKgPC9wPg0KPHA+wqA8L3A+DQo8cD7CoDwvcD4NCjxwPsKgPC9wPg0KPHA+wqA8L3A+DQo8cD7CoDwvcD4NCjxwPsKgPC9wPg0KPHA+wqA8L3A+DQo8cD7CoDwvcD4NCjxwPsKgPC9wPg0KPHA+wqA8L3A+DQo8cD7CoDwvcD4NCjxwPsKgPC9wPg0KPHA+YmFzZTY0ZW5jb2Rpbmc8L3A+PC9w

*update2: I've found the charater ord values in php are: 194 followed by 160 - eg it's two characters. WEIRD. *

Can you post the string encoded in some unambiguous format, such as hex or base64 so that we can see exactly what characters it consists of? — Mark Byers
– Mark Byers, Commented Mar 17, 2011 at 22:32
How would I do that? The paragraph is inserted by tinymce in our cms, cms saves the content into a mysql database and then the cms displays the page from the database. — John Hunt
– John Hunt, Commented Mar 17, 2011 at 22:34
Your fourth preg_replace is what you want. And more importantly: it's working fine. You might change the + into * and add the /ims flags. Otherwise there is something else in your source text. (Existing attributes in the  tags for example?) — mario
– mario, Commented Mar 17, 2011 at 22:36
To test your theory, you can print each character of the empty paragraph using ord(). Or your editor might support printing the hex value of a character, e.g. in Vim, hover over the letter and type ga. — Mikel
– Mikel, Commented Mar 17, 2011 at 22:36
Should it be some other whitespace character, then use /\p{Z}+/u to kill it. — mario
– mario, Commented Mar 17, 2011 at 22:38

mario · Accepted Answer · 2011-03-17 23:00:38Z

7

It's indeed the UTF-8 encoding 11000010 10100000 of NBSP \xA0. As said earlier, this works:

= preg_replace('/<p>\p{Z}*<\/p>/u', '<p class="notmobile"> </p>', $f);

answered Mar 17, 2011 at 23:00

mario

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John Hunt Over a year ago

Thanks Mario, I couldn't figure out how to get your regexp in there properly. Answer accepted!

Xint0 · Accepted Answer · 2011-03-17 22:35:24Z

1

It might be a non-breaking space   ASCII code 0xA0, 160.

Try:

$filecontent  = preg_replace('/<p>\xA0<\/p>/', '<p class="notmobile"> </p>',   $filecontent);

answered Mar 17, 2011 at 22:35

Xint0

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John Hunt Over a year ago

You were heading in the right direction. Funny that C2A0 is displayed as just one character.. I wonder what C2 actually is..

Blender · Accepted Answer · 2011-03-17 22:48:49Z

1

Why not just replace  with ?

$filecontent = str_replace("<p>", "<p class=\"notmobile\">", $filecontent);

Or are you trying to replace all pairs of  tags, regardless of content, with  ?

For tag pairs with only one space in between, try replacing it like so:

$filecontent = str_replace("<p> </p>", "<p class=\"notmobile\"> </p>", $filecontent);

edited Mar 17, 2011 at 22:48

answered Mar 17, 2011 at 22:34

Blender

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3 Comments

John Hunt Over a year ago

Because I only want to replace empty paragrahs generated by tinymce with that, not paragraphs with content.

Blender Over a year ago

Then just replace   with  .

John Hunt Over a year ago

The point was the space wasn't a regular space, it was hex C2A0 (eg two funny characters glued together)

John Hunt · Accepted Answer · 2011-03-17 22:58:40Z

0

$filecontent  = preg_replace('/<p>\xC2\xA0<\/p>/', '<p class="notmobile"> </p>',    $filecontent);

Easy when you realise nothing is as it seems! Modding up useful answers now.

answered Mar 17, 2011 at 22:58

John Hunt

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