In my book it says that LOOPZ works like this...

ECX = ECX - 1
if ECX > 0 and ZF = 1 then jump <label>

Eh? How is it possible for that condition to be true?? if ECX is greater than 0 then surely its not possible for ZF to be 1, thats like saying...

if ECX > 0 and ECX = 0 then jump <label>



What am I missing here?