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br2nl Replace All XHTML/HTML Line Breaks with Newlines in PHP

Answer 1

+9 A:

I would generally say "don't use regex to work with HTML", but, on this one, I would probably go with a regex, considering that   tags generally look like either :

 
or  , with any number of spaces before the /

I suppose something like this would do the trick :

$html = 'this <br>is<br/>some<br />text <br    />!';
$nl = preg_replace('#<br\s*/?>#i', "\n", $html);
echo $nl;

Couple of notes :

starts with <br
followed by any number of white characters : \s*
optionnaly, a / : /?
and, finally, a >
and this using a case-insensitive match, as   would be valid in HTML

Pascal MARTIN 2010-03-12 21:57:32

That's a great explanation of the regex.

Echo 2010-03-12 22:06:32

+1 for breaking down the regex.

markb 2010-03-12 22:24:25

To be very nit-picky =] : `<input type="text" value=" ">` is allowed in html (not xhtml). And in a CDATA section ` ` is "normal" text.

VolkerK 2010-03-12 22:50:32

@VolkerK : humph, true :-) ;; I was writting this using DOM, and when I finished, I saw you posted the same kind of solution I would have proposed *(excepts I used getElementsByName, and not XPath)*, so didn't post it -- maybe I should edit my answer, though, for the sake of completness, as it's been accepted...

Pascal MARTIN 2010-03-13 10:37:50

@Pascal: But this solution is faster and less memory consuming (if this is a matter). If you don't have _completely_ arbitrary documents I'd probably consider these edge-cases acceptable.

VolkerK 2010-03-13 12:12:16

Answer 2

+1 A:

If the document is well-formed (or at least well-formed-ish) you can use the DOM extension and xpath to find and replace all br elements by a \n text node.

$in = '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd"&gt;
<html><head><title>...</title></head><body>abc<br />def<p>ghi<br />jkl</p></body></html>';

$doc = new DOMDOcument;
$doc->loadhtml($in);
$xpath = new DOMXPath($doc);

$toBeReplaced = array();
foreach($xpath->query('//br') as $node) {
    $toBeReplaced[] = $node;
}

$linebreak = $doc->createTextNode("\n");
foreach($toBeReplaced as $node) {
    $node->parentNode->replaceChild($linebreak->cloneNode(), $node);
}

echo $doc->savehtml();

prints

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"&gt;
<html>
<head><title>...</title></head>
<body>abc
def<p>ghi
jkl</p>
</body>
</html>

edit: shorter version with only one iteration

$in = '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd"&gt;
<html><head><title>...</title></head><body>abc<br />def<p>ghi<br />jkl</p></body></html>';

$doc = new DOMDOcument;
$doc->loadhtml($in);
$xpath = new DOMXPath($doc);

$linebreak = $doc->createTextNode("\n");
foreach($xpath->query('//br') as $node) {
  $node->parentNode->removeChild($node);
}

echo $doc->savehtml();

VolkerK 2010-03-12 22:13:31

You don’t need to do two rounds. You can replace the nodes with the first `foreach`.

Gumbo 2010-03-12 22:19:10

That seems to be so ;-) For some (unknown) reason I remembered it to break the xpath iterator.

VolkerK 2010-03-12 22:27:43

Answer 3

A:

From the nl2br comments:

<?php
function br2nl($string){
  $return=eregi_replace('<br[[:space:]]*/?'.
    '[[:space:]]*>',chr(13).chr(10),$string);
  return $return;
}
?>

ssergei 2010-03-12 22:15:56

the posix regular expression module has been deprecated. From the ereg\_replace manual page: "This function has been DEPRECATED as of PHP 5.3.0 and REMOVED as of PHP 6.0.0. Relying on this feature is highly discouraged."

VolkerK 2010-03-12 22:34:42

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br2nl Replace All XHTML/HTML Line Breaks with Newlines in PHP

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