$re = '/<div[^>]*>\K(.+?)(?=<\/div>)/si';
$str = '<div class="d-xl-none">
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbar-top-menu">
<i class="icon-grid3"></i>
</button>
</div>
<div class=\'class_1\'>
<span>test</span>
</div>';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php