PHP quine

<?php

$code = <<<'code_end'
  /*
     This function outputs all of the code used to write this program.
     It effectively makes this program a quine.
  */

  // declare $code (remember it contains the code of this function itself)
  global $code;

  // take care of the initial opening statements
  $initial = "<?php\n\n\$code = <<<'code_end'\n";

  // add the final few lines into an array, which we'll concatenate later
  $lines = array(
    'code_end;',
    '$printing_function = create_function("", $code);',
    '$printing_function();'
  );

  // create a variable containing the closing tag
  // the tag is created via concatenation to prevent it from ending the code
  $closing_tag = '?' . '>';

  // concatenate the $lines array
  $final_lines = "";
  foreach ($lines as $line)
    $final_lines .= $line . "\n\n";

  // send a header to the browser, to show this as text instead of HTML
  header("Content-Type: text/plain");

  // concatenate all the individual parts of the code and output it
  $sourcecode = $initial .
                $code . "\n" . // nowdoc syntax doesn't add the final newline
                $final_lines .
                $closing_tag;
  echo($sourcecode);

code_end;

$printing_function = create_function("", $code);

$printing_function();

?>