array_udiff_assoc和array_diff_uassoc之间的区别是什么？

Question

what is the difference between array_udiff_assoc and array_diff_uassoc

for array_udiff_assoc i get this thing

<?php
 function myfunction($v1,$v2)
 {
 if ($v1===$v2)
   {
   return 0;
   }
 return 1;
 }
 $a1=array("a"=>"Cat","b"=>"Dog","c"=>"Horse");
 $a2=array("a"=>"Cat","b"=>"Horse","c"=>"Dog");
 print_r(array_udiff_assoc($a1,$a2,"myfunction"));
 ?>

result

Array ( [b] Dog [c] => Horse )

also array_diff_uassoc

  <?php
     function myfunction($v1,$v2)
     {
     if ($v1===$v2)
       {
       return 0;
       }
     return 1;
     }
     $a1=array("a"=>"Cat","b"=>"Dog","c"=>"Horse");
     $a2=array("a"=>"Cat","b"=>"Horse","c"=>"Dog");
     print_r(array_diff_uassoc($a1,$a2,"myfunction"));
     ?>

result is same as first one

Array ( [b] Dog [c] => Horse )

Is the have any difference, if have what is that. Php manual does not says that they are alias, as they used to say.

Answer 1

They both do the same, but udiff-assoc compares the DATA with the user supplied function, while diff-uassoc compares the INDEX with the user supplied function.

As an answer to @lonsesomeday : as indicated by the 'u', diff_assoc will use internal functions for all comparisons, and udiff_uassoc uses provided callbacks for index and data comparison.

http://www.php.net/manual/en/function.array-diff-uassoc.php

http://www.php.net/manual/en/function.array-udiff-assoc.php