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How to extract img src, title and alt from html using php?


Question

I would like to create a page where all images which reside on my website are listed with title and alternative representation.

I already wrote me a little program to find and load all HTML files, but now I am stuck at how to extract src, title and alt from this HTML:

<img src="/image/fluffybunny.jpg" title="Harvey the bunny" alt="a cute little fluffy bunny" />

I guess this should be done with some regex, but since the order of the tags may vary, and I need all of them, I don't really know how to parse this in an elegant way (I could do it the hard char by char way, but that's painful).

2015/05/27
1
150
5/27/2015 12:59:05 PM

Accepted Answer

EDIT : now that I know better

Using regexp to solve this kind of problem is a bad idea and will likely lead in unmaintainable and unreliable code. Better use an HTML parser.

Solution With regexp

In that case it's better to split the process into two parts :

  • get all the img tag
  • extract their metadata

I will assume your doc is not xHTML strict so you can't use an XML parser. E.G. with this web page source code :

/* preg_match_all match the regexp in all the $html string and output everything as 
an array in $result. "i" option is used to make it case insensitive */

preg_match_all('/<img[^>]+>/i',$html, $result); 

print_r($result);
Array
(
    [0] => Array
        (
            [0] => <img src="/Content/Img/stackoverflow-logo-250.png" width="250" height="70" alt="logo link to homepage" />
            [1] => <img class="vote-up" src="/content/img/vote-arrow-up.png" alt="vote up" title="This was helpful (click again to undo)" />
            [2] => <img class="vote-down" src="/content/img/vote-arrow-down.png" alt="vote down" title="This was not helpful (click again to undo)" />
            [3] => <img src="http://www.gravatar.com/avatar/df299babc56f0a79678e567e87a09c31?s=32&d=identicon&r=PG" height=32 width=32 alt="gravatar image" />
            [4] => <img class="vote-up" src="/content/img/vote-arrow-up.png" alt="vote up" title="This was helpful (click again to undo)" />

[...]
        )

)

Then we get all the img tag attributes with a loop :

$img = array();
foreach( $result as $img_tag)
{
    preg_match_all('/(alt|title|src)=("[^"]*")/i',$img_tag, $img[$img_tag]);
}

print_r($img);

Array
(
    [<img src="/Content/Img/stackoverflow-logo-250.png" width="250" height="70" alt="logo link to homepage" />] => Array
        (
            [0] => Array
                (
                    [0] => src="/Content/Img/stackoverflow-logo-250.png"
                    [1] => alt="logo link to homepage"
                )

            [1] => Array
                (
                    [0] => src
                    [1] => alt
                )

            [2] => Array
                (
                    [0] => "/Content/Img/stackoverflow-logo-250.png"
                    [1] => "logo link to homepage"
                )

        )

    [<img class="vote-up" src="/content/img/vote-arrow-up.png" alt="vote up" title="This was helpful (click again to undo)" />] => Array
        (
            [0] => Array
                (
                    [0] => src="/content/img/vote-arrow-up.png"
                    [1] => alt="vote up"
                    [2] => title="This was helpful (click again to undo)"
                )

            [1] => Array
                (
                    [0] => src
                    [1] => alt
                    [2] => title
                )

            [2] => Array
                (
                    [0] => "/content/img/vote-arrow-up.png"
                    [1] => "vote up"
                    [2] => "This was helpful (click again to undo)"
                )

        )

    [<img class="vote-down" src="/content/img/vote-arrow-down.png" alt="vote down" title="This was not helpful (click again to undo)" />] => Array
        (
            [0] => Array
                (
                    [0] => src="/content/img/vote-arrow-down.png"
                    [1] => alt="vote down"
                    [2] => title="This was not helpful (click again to undo)"
                )

            [1] => Array
                (
                    [0] => src
                    [1] => alt
                    [2] => title
                )

            [2] => Array
                (
                    [0] => "/content/img/vote-arrow-down.png"
                    [1] => "vote down"
                    [2] => "This was not helpful (click again to undo)"
                )

        )

    [<img src="http://www.gravatar.com/avatar/df299babc56f0a79678e567e87a09c31?s=32&d=identicon&r=PG" height=32 width=32 alt="gravatar image" />] => Array
        (
            [0] => Array
                (
                    [0] => src="http://www.gravatar.com/avatar/df299babc56f0a79678e567e87a09c31?s=32&d=identicon&r=PG"
                    [1] => alt="gravatar image"
                )

            [1] => Array
                (
                    [0] => src
                    [1] => alt
                )

            [2] => Array
                (
                    [0] => "http://www.gravatar.com/avatar/df299babc56f0a79678e567e87a09c31?s=32&d=identicon&r=PG"
                    [1] => "gravatar image"
                )

        )

   [..]
        )

)

Regexps are CPU intensive so you may want to cache this page. If you have no cache system, you can tweak your own by using ob_start and loading / saving from a text file.

How does this stuff work ?

First, we use preg_ match_ all, a function that gets every string matching the pattern and ouput it in it's third parameter.

The regexps :

<img[^>]+>

We apply it on all html web pages. It can be read as every string that starts with "<img", contains non ">" char and ends with a >.

(alt|title|src)=("[^"]*")

We apply it successively on each img tag. It can be read as every string starting with "alt", "title" or "src", then a "=", then a ' " ', a bunch of stuff that are not ' " ' and ends with a ' " '. Isolate the sub-strings between ().

Finally, every time you want to deal with regexps, it handy to have good tools to quickly test them. Check this online regexp tester.

EDIT : answer to the first comment.

It's true that I did not think about the (hopefully few) people using single quotes.

Well, if you use only ', just replace all the " by '.

If you mix both. First you should slap yourself :-), then try to use ("|') instead or " and [^ΓΈ] to replace [^"].

2017/05/23
204
5/23/2017 12:03:05 PM


Just to give a small example of using PHP's XML functionality for the task:

$doc=new DOMDocument();
$doc->loadHTML("<html><body>Test<br><img src=\"myimage.jpg\" title=\"title\" alt=\"alt\"></body></html>");
$xml=simplexml_import_dom($doc); // just to make xpath more simple
$images=$xml->xpath('//img');
foreach ($images as $img) {
    echo $img['src'] . ' ' . $img['alt'] . ' ' . $img['title'];
}

I did use the DOMDocument::loadHTML() method because this method can cope with HTML-syntax and does not force the input document to be XHTML. Strictly speaking the conversion to a SimpleXMLElement is not necessary - it just makes using xpath and the xpath results more simple.

2008/09/26

If it's XHTML, your example is, you need only simpleXML.

<?php
$input = '<img src="/image/fluffybunny.jpg" title="Harvey the bunny" alt="a cute little fluffy bunny"/>';
$sx = simplexml_load_string($input);
var_dump($sx);
?>

Output:

object(SimpleXMLElement)#1 (1) {
  ["@attributes"]=>
  array(3) {
    ["src"]=>
    string(22) "/image/fluffybunny.jpg"
    ["title"]=>
    string(16) "Harvey the bunny"
    ["alt"]=>
    string(26) "a cute little fluffy bunny"
  }
}
2008/09/26

The script must be edited like this

foreach( $result[0] as $img_tag)

because preg_match_all return array of arrays

2010/12/18

You may use simplehtmldom. Most of the jQuery selectors are supported in simplehtmldom. An example is given below

// Create DOM from URL or file
$html = file_get_html('http://www.google.com/');

// Find all images
foreach($html->find('img') as $element)
       echo $element->src . '<br>';

// Find all links
foreach($html->find('a') as $element)
       echo $element->href . '<br>'; 
2014/01/27

I used preg_match to do it.

In my case, I had a string containing exactly one <img> tag (and no other markup) that I got from Wordpress and I was trying to get the src attribute so I could run it through timthumb.

// get the featured image
$image = get_the_post_thumbnail($photos[$i]->ID);

// get the src for that image
$pattern = '/src="([^"]*)"/';
preg_match($pattern, $image, $matches);
$src = $matches[1];
unset($matches);

In the pattern to grab the title or the alt, you could simply use $pattern = '/title="([^"]*)"/'; to grab the title or $pattern = '/title="([^"]*)"/'; to grab the alt. Sadly, my regex isn't good enough to grab all three (alt/title/src) with one pass though.

2010/09/28

Source: https://stackoverflow.com/questions/138313
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