In my flying vampire script I've got a block that uses an array to keep track of everyone that sees you, and make them attack you when you land. Here's how I've done it:

array_var AngryMobshort ilong xref foo

(...)

let AngryMob := ar_construct ; <- This is called once when you start flying, will it free up the memory previously used by that array if it already existed?

(...)


; This runs every frame while flying

;MOBGATHERER	set foo to getfirstref 35 3	while foo		if foo.getDead != 1 && foo.getdisabled != 1 && foo.isactorevil != 1 && foo.getfactionrank Vampirefaction != 0			if (foo.getdetected player || foo.getdetected flyer) && foo != player && foo != flyer				let x := ar_find foo AngryMob				if x < 0 ;					if foo.isguard						foo.startcombat flyer						ar_insert AngryMob 0 Foo					else						if foo.getitemcount tVampSpookme < 1							foo.additem tVampSpookMe 1							ar_insert AngryMob 0 Foo						endif					endif				endif			endif		endif 		set foo to getnextref	loop	set foo to 0

(...)

; This is part of a block that runs once when you land. Sadly "while eval ar_size AngryMob > 0" does not compute.

set i to 0	let x := ar_size AngryMob	if x > 0		while (i != 1 && foo)			let foo := AngryMob[0]			if foo.getLOS player || foo.getdetected player				foo.moddisposition player -50				foo.startcombat player			endif			ar_erase AngryMob 0			let x := ar_size AngryMob			if x == 0				set i to 1			endif		loop	endif 

My question is, will this slowly eat up memory if I construct a new array every time? Do I have to construct the array only at the first time the quest script runs?
Also, when I erase an array element, am I deleting the object itself or just a pointer to it? I'd rather not have people disappearing as soon as I land.
Uh, and do I need OBSE v0019 for this?

EDIT: I realise why my script has been crashing: "x" needs to be a Long or a Float as ar_find returns a very large number if it can't find the target! Also, I have to use Let in more cases, and even though GetNextRef will compile when supplied with parameters, it will crash the script! Still, will this create a memory leak?

If you call the ar_construct command on a variable that already stores an array, then that variable is reset and the array disappears. (If you want to be sure, you could always use ar_null). So I wouldn't worry too much about that.

Regarding your comment that eval ar_size AngryMob > 0 won't work...try parentheses:
While eval ((ar_size AngryMob) > 0)
You can also try removing the > 0...it should be unnecessary.

Aye, plus there was some other stuff in there that didn't work as it should either. I really need to stop drink'n'codeing.