PHP Parse HTML code

How can I parse HTML code held in a PHP variable if it something like:

T1
Lorem ipsum.
T2
The quick red fox...
T3
... jumps over the lazy brown FROG!

I want to only get the text that's between the headings and I understand that it's not a good idea to use Regular Expressions.

Answer

Use PHP Document Object Model:

   $str = '
T1
Lorem ipsum.
T2
The quick red fox...
T3
... jumps over the lazy brown FROG';
   $DOM = new DOMDocument;

   $DOM->loadHTML($str);

   //get all H1
   $items = $DOM->getElementsByTagName('h1');

   //display all H1 text
   for ($i = 0; $i < $items->length; $i++)
        echo $items->item($i)->nodeValue . "
";
?>

This outputs as:

 T1
 T2
 T3

---

[EDIT]: After OP Clarification:

If you want the content like Lorem ipsum. etc, you can directly use this regex:

   $str = '
T1
Lorem ipsum.
T2
The quick red fox...
T3
... jumps over the lazy brown FROG';
   echo preg_replace("#.*?#", "", $str);
?>

this outputs:

Lorem ipsum.The quick red fox...... jumps over the lazy brown FROG