- array_slice: documentation ( source)
- preg_match_all: documentation ( source)
- var_export: documentation ( source)
<?php
$text = <<<TEXT
<div class="myclass" id="id123" data-foo="bar">content</div>
<div class="myclass" id="id123" data-foo="bar" >content</div>
<div class="myclass" id="id123" data-foo="bar" data-baz="qux">content</div>
<div class="myclass" id="id123" data-foo="bar" data-baz="qux" >content</div>
TEXT;
preg_match_all('~<div class="myclass" id="(.*?)" data-foo="(.*?)" ?(?:data-baz="(.*?)" ?)?>~', $text, $matches);
var_export(array_slice($matches, 1));