Steven D'Aprano wrote: > On Fri, 07 Sep 2007 11:12:05 +0200, Wildemar Wildenburger wrote: > >> Lawrence D'Oliveiro wrote: >>> In message <[EMAIL PROTECTED]>, Chris >>> Mellon wrote: >>> >>>> On 9/5/07, Steve Holden <[EMAIL PROTECTED]> wrote: >>>>> Doran, Harold wrote: >>>>>> Is there a way to check if the first element of y is null? >>>>>> >>>>> len(y[0]) == 0 >>>>> >>>> Better spelled as >>>> >>>> if y[0]: >>> Not a good idea. >> Why not? > > > What happens if y is an empty list? > > An exception pops up, of course ;).
It all depends on the (intended) semantics of the program; the original question sounds like that list is supposed to have at least one element at that point, so there is no problem. And if it's not then that has to be dealt with, but that is not the problem here. So the usual way to check if the first element of a list y is True in a boolean context is indeed "if y[0]:" (or for False of course "if not y[0]:"). /W -- http://mail.python.org/mailman/listinfo/python-list
