Sorting with usaort

Problem: You have an array of objects or a multidimentional arrays where the key of the first array has some meaning. It could be a id or something else. You want to sort the array and maintain the key=>value association.

Some may then proceed to loop the array and sort it in a loop, however there is a easier method.

Sollution: Enters the php function Uasort. This function takes an array as the first argument and the name of a comparison function as a string. If you want to use a static method in a class you can use array("ClassName", "staticFuncName"). The user comparison function takes two arguments that correspond to two elements in your array. Do some comparison on them and return 0, -1 or 1 to adjust how you want them sorted. The function takes care of looping all elements and applying the comparison func correctly.

$testArray = array(
 "testing3" => array("timestamp" => 11220022, 
                      "name" =>"testing3"),
  "testing" => array("timestamp" => 11220011, 
                     "name" =>"testing"),
   "testing2" => array("timestamp" => 11220033, 
                       "name" =>"testing2"));

uasort($testArray, "sortTimestamp");
print_r($testArray);

function sortTimestamp($foo, $bar){
  if($foo["timestamp"] == $bar["timestamp"]){
    return 0;
  }else if($foo["timestamp"] > $bar["timestamp"]){
    return 1;
  }else{
    return -1;
  }
}

This code outputs:

Array
(
    [testing] => Array
        (
            [timestamp] => 11220011
            [name] => testing
        )

    [testing3] => Array
        (
            [timestamp] => 11220022
            [name] => testing3
        )

    [testing2] => Array
        (
            [timestamp] => 11220033
            [name] => testing2
        )

)

Now that is rather neat if you ask me :)