Question

I have read about uksort in the PHP manual but it is very difficult to understand.

Can any one help me out?

Here is an example:

 <?php  
 function my_sort($x, $y)  
 {  
   if ($x == $y) return 0;  
   return ($x > $y) ? -1 : 1;  
 }  
 $people = array(
   "10" => "javascript",  
   "20" => "php", "60" => "vbscript",  
   "40" => "jsp");  
 uksort($people, "my_sort");  
 print_r($people);  
 ?>

What is happening here?

Answer 1

As said in the manual, your function (my_sort in this case) should return:

• a negative integer (in this case -1) if you consider $a to be less than $b
• a positive integer if you consider $a to be greater than $b
• 0 if you consider them to be the same.

As you may have guessed, uksort will use your comparison function to see in which order the elements should be in the sorted array. It will call your function multiple times, every time with two keys. You compare those to keys to each other and give your result back.

The idea is that you can program your own comparison function which does something non-trivial, for example if you want a certain key to always be first. Your trivial example can use the regular krsort instead.