Replace the last occurrence of
tag in a string

Question

I'm looking to replace the last occurrence of P tag in a string.

$bodytext = preg_replace(strrev("/<p>/"),strrev('<p class="last">'),strrev($bodytext),1);
$bodytext = strrev($bodytext);

This works, but can it be done without using strrev? Is there a regex solution?

Something like :

$bodytext = preg_replace('/<p>.?$/', '<p class="last">', $bodytext);

Any help would be greatly appreciated.

My shortened version:

$dom = new DOMDocument();
$dom->loadHTML($bodytext);
$paragraphs = $dom->getElementsByTagName('p');
$last_p = $paragraphs->item($paragraphs->length - 1);
$last_p->setAttribute("class", "last");
$bodytext = $dom->saveHTML();

[Don't use regexes for parsing HTML](http://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags/1732454#1732454). Use the DOM instead, Look into [DOMDocument](http://www.php.net/manual/en/book.dom.php). — John Conde, Mar 23 '14 at 02:56
If you're doing that so that you can style the last `p`, you should consider using `p:last` instead. — pguardiario, Mar 23 '14 at 04:15
That was the first thing I looked at, but I would still like to support IE 7 & 8. — Brian Smith, Mar 23 '14 at 17:04

score 1 · Accepted Answer · answered Mar 23 '14 at 03:08

1

Some people will complain that DOMDocument is more verbose for parsing HTML then a regex. But verbosity is okay if it means using the right tool for the job.

$previous_value = libxml_use_internal_errors(TRUE);
$string = '<p>hi, mom</p><p>bye, mom</p>';
$dom = new DOMDocument();
$dom->loadHTML($string);
$paragraphs = $dom->getElementsByTagName('p');
$last_p = $paragraphs->item($paragraphs->length - 1);
$last_p->setAttribute("class", "last");
$new_string = preg_replace('/^<!DOCTYPE.+?>/', '', str_replace( array('<html>', '</html>', '<body>', '</body>'), array('', '', '', ''), $dom->saveHTML()));
libxml_clear_errors();
libxml_use_internal_errors($previous_value);

echo htmlentities($new_string);
// <p>hi, mom</p><p class="last">bye, mom</p>

See it in action

answered Mar 23 '14 at 03:08

John Conde

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I appreciate the code example. I will have a look and test the parse speed results - but it does seem excessive considering the string is always around 500 characters and only contains one link and 2 sets of
tags. – Brian Smith Mar 23 '14 at 03:34
1

It's going to be fast. Don't associate speed with lines of code. And don;t let speed be the only factor. Regex's aren't made for processing HTML. DOMDocument is. – John Conde Mar 23 '14 at 03:40
I modified my post - is there any issues if I used my shortened version of your code? – Brian Smith Mar 23 '14 at 03:56
There won't be any issues unless the string you pass contains invalid HTML at any point. Then you will get warnings generated by PHP. – John Conde Mar 23 '14 at 13:29
Ok thanks, CKEditor is handling the html output so that shouldn't be an issue. – Brian Smith Mar 23 '14 at 17:01

score 0 · Answer 2 · answered Mar 23 '14 at 04:12

0

How about using simple html dom?

require_once('simple_html_dom.php');

$string = '<p>hi, mom</p><p>bye, mom</p>';
$doc = str_get_html($string);
$doc->find('p', -1)->class = 'last';
echo $doc;
// <p>hi, mom</p><p class="last">bye, mom</p>

answered Mar 23 '14 at 04:12

pguardiario

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Replace the last occurrence of tag in a string

2 Answers2

Replace the last occurrence of
tag in a string