Sorting array within a class

griffinmt

Having trouble using usort within a class.

Example:

class User {
var $fn;
var $ln;
var $id;
function User() { ...}
...
}
class Users {
var $list = array();
function Users() {...}
function addUser($U) {array_push($this->list,$U);}
...
}

The above are two classes, the second (Users) is an array of User class objects. From within Users, I would like to sort the array (using usort) such that the elements are in sequence by User->ln

Cannot get it to invoke the comparison function and the result is a somewhat randome sequence. :rolleyes:

What is the most efficient way to call the usort and code the associated comparision function?

Thanks

Shrike

You have to pass the arguments as an array:

usort($obj->var, array($object_reference, "compare_function"));

Check out example 3 at the [MAN]usort[/MAN] page.

griffinmt


class User 
{ 
   var $fn; 
   var $ln; 
   var $id; 

   function User() { ...} 
... 
} 

class Users 
{ 
   var $list = array();  

   function Users() {...} 

   function addUser($U) {array_push($this->list,$U);} 
... 

   function cmp_user($x,$y)
   {
      if ($x->ln < $y->ln) { return -1; }
      else if ($x->ln > $y->ln) { return 1; }
      else return 0;
   }

   function sortit()
   {
      usort($this->list, array("User", "cmp_user");
   }
}

Does this seem correct for my example??

Thanks

Shrike

You probably want

usort($this->list, array($this, "cmp_user"));

griffinmt

But, that will reference the Users class, and the values to be compared are its elements, which are actually values of the User class????
Anyway, using $this does not work. And I cannot figure out just how to reference the target objects.

EDIT:
I just added a var_dump() for the first parm in the compare routine (using $this in the usort call as suggested) and do indeed seem to be getting each User object being passed. After a bit more 'carefull' checking, I found a typo in the compare routine (those "i" and "l" look the same to this old fart!!).

Anyway, I got it working as expected.

Thanks a great deal for your assistance.
Martyn