Calculating diff between two fields

This compares the values of two text fields using PEAR.

$path = '/pathToPearsParentDirectory/pear/PEAR';
set_include_path(get_include_path() . PATH_SEPARATOR . $path);

require_once 'PEAR.php';
include_once "Text/Diff.php";
include_once "Text/Diff/Renderer.php";
include_once "Text/Diff/Renderer/inline.php";

$diff = &new Text_Diff('auto', array(array($node->field_nameOfOneFieldToCompare[0]['value']), array($node->field_nameOfOtherFieldToCompare[0]['value'])));
$renderer = &new Text_Diff_Renderer_inline();

$node_field[0]['value'] = $renderer->render($diff); 

Notes:

• Remove the <?php and ?> from the code before pasting!
• You must install PEAR's Text_Diff module. This isn't part of the standard install.
• The $path and set_include_path lines are unnecessary if your PHP engine's include_path already includes the PEAR root directory. I had to override because I had to install my own copy of PEAR; my web host's version didn't include Text_Diff and was too out of date to allow the install.
• Until #367281: Longtext field is broken is fixed, you should use varchar or text instead of longtext.

More details at http://arencambre.com/blog/2009/05/17/how-i-got-field-diffs-working-with...