Ytukyg

When I try to do str_replace() or preg_replace() within the function, the content does not change.

Content in variable $sadrzaj:

$sadrzaj = '<p>asdasdasds</p><p><a href="http://www.example.com/wp-content/uploads/2018/11/image.jpg" itemprop="url" title="some title"><img alt="some alt title" class="alignnone size-full wp-image-243618" src="http://www.example.com/wp-content/uploads/2018/11/image.jpg" width="940" height="529"></a></p>asdasdasd<p>asdasd</p><h3>asdada</h3><p><a href="http://www.example.com/wp-content/uploads/2018/11/image_02.jpg" itemprop="url" title="some title 02"><img alt="some alt title 02" class="alignnone size-full wp-image-243653" src="http://www.example.com/wp-content/uploads/2018/11/image_02.jpg" width="940" height="529"></a></p><h3>asdasd</h3>';

My function to_je_to():

function to_je_to($content){

    preg_match_all('/<img (.*?)/>/', $content, $images);

    //print_r($images);



    if(!is_null($images)){

        foreach($images[1] as $index => $value){

            if(strpos($images[1], 'size-full') !== false){

            //if(preg_match('/alt=""/', $value)){

                $new_img = preg_replace('<img', "<img data-example", $images[0][$index]);

                $content = preg_replace($images[0][$index], $new_img, $content);

            }

        }

    }

    echo $content; // return no difference

}

Calling the function to_je_to($sadrzaj); - nothing changes.

If there is class with "size-full", find this images and replace their tag with <img data-example ...>.

Even str_replace() or preg_replace() is not working.

What am I doing wrong?

Thanks

What you're doing wrong is parsing HTML with a regular expression. You should use a proper DOM parser and then you can use XPath queries to isolate your desired elements.

<?php

$sadrzaj = '<p>asdasdasds</p><p><a href="http://www.example.com/wp-content/uploads/2018/11/image.jpg" itemprop="url" title="some title"><img alt="some alt title" class="alignnone size-full wp-image-243618" src="http://www.example.com/wp-content/uploads/2018/11/image.jpg" width="940" height="529"></a></p>asdasdasd<p>asdasd</p><h3>asdada</h3><p><a href="http://www.example.com/wp-content/uploads/2018/11/image_02.jpg" itemprop="url" title="some title 02"><img alt="some alt title 02" class="alignnone size-full wp-image-243653" src="http://www.example.com/wp-content/uploads/2018/11/image_02.jpg" width="940" height="529"></a></p><h3>asdasd</h3>';



function to_je_to($content) {

    $dom = new DomDocument;

    $dom->loadHTML($content, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD);

    $xp = new DomXpath($dom);

    $nodes = $xp->query("//img[contains(concat(' ', normalize-space(@class), ' '), ' size-full ')]");

    foreach ($nodes as $img) {

        $img->setAttribute("data-example", "");

    }

    return $dom->saveHTML();

}

echo to_je_to($sadrzaj);

And, commenting on your original code: $images will never be null, it will always be an array. Why loop over $images[1] and then replace values based on $images[0]? There's no use of the group match (.*?) at all so it doesn't need to be there. Neither of the preg_replace() calls in the loop use delimiters around the expression to search, so both would have failed with errors. And there is a very big difference between echo and return.

There are a few issues with your function (in your preg_match_all, and preg_replace). Also, you need to be more sophisticated in terms of matching the class on the <img> tag. Overall, you would be better off using the built-in DOMDocument class as the other answer proposes. If you want to keep using regex, this function should fix the issues you had.

function to_je_to($content){

    preg_match_all('/<img[^>]+>/', $content, $images);



    if(!is_null($images)){

        foreach($images[0] as $index => $value){

            if(preg_match('/class="[^"]*(?<=["s])size-full[s"]/', $value)){

                $new_img = str_replace('<img', '<img data-example', $value);

                $content = preg_replace('/' . preg_quote($value, '/') . '/', $new_img, $content);

            }

        }

    }

    return $content; // return no difference

}

echo to_je_to($sadrzaj);

Demo on 3v4l.org