I agree with most of what's been said so far. OOP can be useful in PHP, but learning to use it properly can be a big investment of time and effort, and if you're never planning to use it for anything but PHP, it may not worth it.
Basically, classes are a combination of a structure (or an associative array in PHP) and a set of functions related to it. Classes also provide a kind of namespacing, preventing conflicts between global variables.
PHP supports inheritence and polymorphism, which can be useful in dynamic programming. As a trivial example, suppose you want to give each user a pet that follows them through the website. You let them choose a cat or dog. your classes might look something like this:
class animal
{
var $sound;
function display() {}
function talk()
{
echo $sound;
}
}
class cat extends animal
{
function cat()
{
$this->sound = "meow";
}
function display()
{
echo '<img src="cat.gif" width="80" height="60">';
}
}
class dog extends animal
{
function dog()
{
$this->sound = "bow wow";
}
function display()
{
echo '<img src="dog.gif" width="50" height="80">';
}
}
Now you can have code like this:
if ($user_choice == "dog")
$pet = new dog();
else
$pet = new cat();
// notice that here we don't need to know which pet they chose
$pet->display();
if ($bought_petfood)
$pet->talk();
You could do the same thing without OOP, but the OO version (if properly written) is easier to maintain and extend. If it's badly written, the OO version could be more difficult to maintain and extend, which is why it's a good idea to really take the time to learn OOP if you decide it's something you want to use.
