Sort array by object property in PHP?

Question

If I have an object as such:

class Person {
  var $age;
  function __construct($age) {
    $this->age = $age;
  }
}

and I have any array

Answer 1

One observation is that if the source of the data is from a database, it's probably faster to sort using SQL than it would be within PHP. Of course this is moot if the data source is from a CSV or XML file.