Storing object into Array - OOP

Hello All,
Can I store objects into an array?

$anArray[$index] = $anObject;
$anArray[$index]->aMethod();

I have problems executing the above code. Does anyone knows a better/correct way of doing it? How do I invoke a method belonging to that object?

Thanks in advance!

In PHP3 I had trouble with this sort of thing, but not in PHP4. What version are you using?

Hi scollo,
Thanx I will have my php upgraded. Do you know whether is there a function which could determine the class of an object? for instance, in java i could use ... "instanceof" to check whether a particular object belong to a particular class?