Checking whether list element exists

[mensanator at aol.com]

On Apr 7, 10:37�am, Wojciech Mula
<wojciech_m... at poczta.null.onet.pl.invalid> wrote:
> Rehceb Rotkiv wrote:
> > I want to check whether, for example, the element myList[-3] exists. So
> > far I did it like this:
>
> > index = -3
> > if len(myList) >= abs(index):
> >    print myList[index]
>
> IMHO it is good way.
>
> > Another idea I had was to (ab-?)use the try...except structure:
>
> > index = -3
> > try:
> >    print myList[index]
> > except:
> >    print "Does not exist!"
>
> In general case it won't work, because lists accept negative indexes:http://docs.python.org/lib/typesseq.html, 3rd note.

Why? What does negative indexes have to do with it?

>>> a = [1,2]
>>> index = -3
>>> try:
	print a[index]
except:
	print 'does not exist'


does not exist



>
> w.