PHP: file_get_contents() or simlar

[toString]

To make things easier to explain/understand I have 2 files similar to this:


PHP file A:

<?
  if (...) {
    echo x;
  } else {
    echo y;
  }
?>

PHP file B:

<?
  $output = file_get_contents(fileA.php);
  .
  .
  [do some things first !important]
  .
  .
  echo $output;
?>

Hopefully makes sense, but the trouble is $output has the echo of both x and y, not just one (as you might expect from and if statement!) I assume this is something to do with using the file_get_contents

EDIT: I just worked out it's not actually 'executing' PHP fileA! Is there a function that will grab the output of the file, and store it as my $output string?