[Tutor] Testing for empty list
alan.gauld at btinternet.com
Mon Oct 19 21:01:58 CEST 2009
"Katt" <the_only_katala at verizon.net> wrote
> Just a newbie question, but when would you test for an empty list?
When you are processing a list such that you are deleting items as you go.
When the list is empty stop processing!
And Python helps you do that by treating an empty list as a False
boolean value so you can do
process items from myList
This will keep on processing myList until all the items have
been deleted. Note, this could be more times than the number
of items in the list...for example:
counter = 0
myList = [12,24]
nines = 
counter += 1
print "iteration number", counter
index = 0
while index < len(myList): # copes with disappearing members
if myList[index] % 9 == 0: # is it divisible by 9?
del(myList[index]) # remove from list
else: myList[index] -= 1
index += 1
> while len(mylist) > 0:
> continue program
> print "mylist is empty
That is the same as
print 'mylist is empty'
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