How do I get the type of a struct?

I have a struct called "area" from which "circle", "rectangle", & "triangle" extend.
My search function takes an area as argument but how can I check which kind of area it has been given?

I'm looking for something like:
getType(struct)

Or maybe:
struct.type

I think it is like .getTypeId() should be in the manual.

Cheers but getType() only works for structs that extend an interface. Right now I'm just extending area with an empty interface as a workaround.

Yes, it is all right that vJass forces you to use an interface when your design seems to be polymorphism-based.