Online PHP editor | output for pqjvP

@ 2019-01-27T03:48:18Z

<?php

$html = <<<'HTML'
<body>
  <main>
    <div>
      Lorem ipsum dolor sit amet consectetur adipisicing elit.
    </div>
    <p>
      Incidunt expedita laudantium aliquid unde explicabo.
    </p>
    <span>
      Velit eveniet alias minima vitae libero labore.
    </span>
  </main>
</body>
HTML;

$dom = new DOMDocument;
@$dom->loadHTML($html, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD);
$xpath = new DomXPath($dom);
$entry = $xpath->query('//main/node()');

$content = '';
foreach($entry as $element) {
  $content .= $dom->saveHTML($element);
}

/////////////////////////////////////////////////////////////////////////////////
// Как дальше искать внутри переменной «$content» (без xPath) ?
/////////////////////////////////////////////////////////////////////////////////

$subcontent = '';
foreach($content->getElementsByTagName('*') as $node) {
  $subcontent .= $dom->saveHTML($node);
}
echo $subcontent; // не работает

Output for 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.25, 8.4.1 - 8.4.13: Fatal error: Uncaught Error: Call to a member function getElementsByTagName() on string in /in/pqjvP:34 Stack trace: #0 {main} thrown in /in/pqjvP on line 34
Process exited with code 255.
Output for 5.6.0 - 5.6.40: Fatal error: Call to a member function getElementsByTagName() on string in /in/pqjvP on line 34
Process exited with code 255.
Output for 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.38: Fatal error: Call to a member function getElementsByTagName() on a non-object in /in/pqjvP on line 34
Process exited with code 255.
Output for 4.4.2 - 4.4.9, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17: Parse error: syntax error, unexpected T_SL in /in/pqjvP on line 3
Process exited with code 255.
Output for 4.3.0 - 4.3.1, 4.3.5 - 4.3.11, 4.4.0 - 4.4.1, 5.0.0 - 5.0.5: Parse error: parse error, unexpected T_SL in /in/pqjvP on line 3
Process exited with code 255.
Output for 4.3.2 - 4.3.4: Parse error: parse error in /in/pqjvP on line 3
Process exited with code 255.

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