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I'm trying to use regex to replace source attribute (could be image or any tag) in PHP.

I've a string like this:

$string2 = "<html><body><img src = 'images/test.jpg' /><img src = 'http://test.com/images/test3.jpg'/><video controls="controls" src='../videos/movie.ogg'></video></body></html>";

And I would like to turn it into:

$string2 = "<html><body><img src = 'test.jpg' /><img src = 'test3.jpg'/><video controls="controls" src='movie.ogg'></video></body></html>";

Heres what I tried :

$string2 = preg_replace("/src=["']([/])(.*)?["'] /", "'src=' . convert_url('$1') . ')'" , $string2);
echo htmlentities ($string2);

Basically it didn't change anything and gave me a warning about unescaped string.

Doesn't $1 send the content of the string ? What is wrong here ?

And the function of convert_url is from an example I posted here before : 

function convert_url($url)
{
    if (preg_match('#^https?://#', $url)) {
        $url = parse_url($url, PHP_URL_PATH);
    }
    return basename($url);
}

It's supposed to strip out url paths and just return the filename.

share|improve this question
the original string and what you want to turn it into are both empty strings -- is something missing? – ametren May 18 '12 at 19:04
try to replace the " with \" – Mageek May 18 '12 at 19:06
Just edited it back. – Ashesh May 18 '12 at 19:07
1  
You really shouldn't parse HTML with regex. You should find a pretty comprehensive answer as to why if you search SO. In the meantime, may I suggest DOM or SimpleXML – GordonM May 18 '12 at 20:34
i mean try to replace in the regex all the " into \" but not the first and the last – Mageek May 19 '12 at 4:02
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2 Answers

up vote 0 down vote accepted

You have to use the e modifier.

$string = "<html><body><img src='images/test.jpg' /><img src='http://test.com/images/test3.jpg'/><video controls=\"controls\" src='../videos/movie.ogg'></video></body></html>";

$string2 = preg_replace("~src=[']([^']+)[']~e", '"src=\'" . convert_url("$1") . "\'"', $string);

Note that when using the e modifier, the replacement script fragment needs to be a string to prevent it from being interpreted before the call to preg_replace.

share|improve this answer
up vote 8 down vote

Don't use regular expressions on HTML - use the DOMDocument class.

$html = "<html>
           <body>
             <img src='images/test.jpg' />
             <img src='http://test.com/images/test3.jpg'/>
             <video controls='controls' src='../videos/movie.ogg'></video>
           </body>
         </html>";

$dom = new DOMDocument;  
libxml_use_internal_errors(true);

$dom->loadHTML( $html ); 
$xpath = new DOMXPath( $dom );
libxml_clear_errors();

$doc = $dom->getElementsByTagName("html")->item(0);
$src = $xpath->query(".//@src");

foreach ( $src as $s ) {
  $s->nodeValue = array_pop( explode( "/", $s->nodeValue ) );
}

$output = $dom->saveXML( $doc );

echo $output;

Which outputs the following:

<html>
  <body>
    <img src="test.jpg">
    <img src="test3.jpg">
    <video controls="controls" src="movie.ogg"></video>
  </body>
</html>
share|improve this answer
The dom document class is not very helpful if it is html embedded inside another HTML tag like <script></script> for e.g. – Ashesh May 18 '12 at 19:08
@Ashesh I'm not I follow. You showed us PHP code - I'm showing you the solution. – Jonathan Sampson May 18 '12 at 19:11
Well I'm sorry I should have been more clear. Here's what I'm talking about: "<html><head><script>var html = '<img src = /images/test.jpg/>'</script></head><body></html>". In this case, the domdocument would not pickup on the image tag inside the javascript. That's why I need to use regex. – Ashesh May 18 '12 at 19:13
@Ashesh The code above will work on the PHP string you have provided here. It converts the src elements to point only to the filename. – Jonathan Sampson May 18 '12 at 19:29
Sometimes it's not a good idea to load HTML parser. Especcialy on a short predefined text values (e.g. <img alt="smth" src="smwhr"/>), where only src="" and alt="" could vary. – BasTaller Jun 19 '12 at 14:40

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