Функция PHP xdiff_string_diff

string xdiff_string_diff ( string str1, string str2 [, int context [, bool minimal]] )

xdiff_string_diff makes unified diff of strings str1 and str2. context indicated how many lines of context you want to include in diff result. Set minimal to TRUE if you want to minimalize size of diff (can take a long time).

Замечание: This function doesn't work well with binary strings. To make diff of binary strings use xdiff_string_diff_binary.

Returns string with result or FALSE if an internal error happened.

xdiff_string_diff() example: The following code makes unified diff of two articles.

<?php
   $old_article = file_get_contents('./old_article.txt');
   $new_article = $_REQUEST['article']; /* Let's say that someone pasted a new article to html form */

   $diff = xdiff_string_diff($old_article, $new_article, 1);
   if (is_string($diff)) {
      echo "Differences between two articles: ";
      echo $diff;
   }
?>

See also xdiff_file_diff.