(PECL xdiff >= 0.2.0)
xdiff_file_merge3 — Merge 3 files into one
$old_file
   , string $new_file1
   , string $new_file2
   , string $dest
   ) : mixed
   Merges three files into one and stores the result in a file dest. 
   The old_file is an original version while new_file1
   and new_file2 are modified versions of an original.   
  
old_filePath to the first file. It acts as "old" file.
new_file1
       Path to the second file. It acts as modified version of old_file.
      
new_file2
       Path to the third file. It acts as modified version of old_file.
      
dest
       Path of the resulting file, containing merged changed from both new_file1 and
       new_file2.
      
   Returns TRUE if merge was successful, string with rejected chunks if
   it was not or FALSE if an internal error happened.
  
Example #1 xdiff_file_merge3() example
The following code merges three files into one.
<?php
$old_version = 'original_script.php';
$fix1 = 'script_with_fix1.php';
$fix2 = 'script_with_fix2.php';
$errors = xdiff_file_merge3($old_version, $fix1, $fix2, 'fixed_script.php');
if (is_string($errors)) {
    echo "Rejects:\n";
    echo $errors;
}
?>