I'm confused. Why is it that when I say "while len(list) < 5:", I get
5 items in my list.
If I say "while len(list) < 6:", I get 6 items in the list and so on.
I would think if I said "less than 5", I would get 4 items.
Can anyone explain this?
Thanks.
R.D.
# Start an empty list
list = []
while len(list) < 5:
# Get a random number between 1 & 100
num = random.randint(1,100)
# Make sure there are no duplicates
if num not in list:
# Append each number to the list
list.append(num)
print list 7 1299
DataSmash wrote: I'm confused. Why is it that when I say "while len(list) < 5:", I get 5 items in my list. If I say "while len(list) < 6:", I get 6 items in the list and so on. I would think if I said "less than 5", I would get 4 items. Can anyone explain this?
Yes - you loop until the condition is _not_ fullfilled anymore. Which means
that if the list has a length of five, the len(l) < 6 is true, and
appending makes it len(l) == 6 - which then will fail your condition.
So - you need to loop one time less, by doing
while len(l) < 6 - 1:
...
diez
Em Qui, 2006-03-23 Ã*s 08:31 -0800, DataSmash escreveu: I'm confused. Why is it that when I say "while len(list) < 5:", I get 5 items in my list.
"while len(list) < 5:" implies that the loop will stop only when
len(list) >= 5.
HTH,
--
Felipe.
DataSmash: I'm confused. Why is it that when I say "while len(list) < 5:", I get 5 items in my list.
Because the last time when len(list) was < 5, the block of code following
the while executed and did something to the list to give it a length >= 5
(otherwise the block of code would be executed again and it wouldn't have
been the last time).
list.append(num)
There you have it.
--
René Pijlman
Wat wil jij leren? http://www.leren.nl
You're wanting it to stop when the len(list) == 4, right? The easiest
way to change the logic would be to say
while len(list) != 4:
but that could get you into trouble later on. The problem with the
len(list) < 5 expression is that the loop will run "one more time" as
long as len(list) == 4 adding another item to the list giving you one
more than you wanted. If you wanted, you could put your len() check
inside the loop:
# Start an empty list
list = []
while 1:
# Get a random number between 1 & 100
num = random.randint(1,100)
# Make sure there are no duplicates
if num not in list:
# Append each number to the list
list.append(num)
if len(list) == 4:
# Break if we've reached desired length.
break
print list
I hope this gives you some ideas.
R.D.> I'm confused. Why is it that when I say "while len(list) < 5:", I
R.D.> get 5 items in my list. If I say "while len(list) < 6:", I get 6
R.D.> items in the list and so on. I would think if I said "less than
R.D.> 5", I would get 4 items. Can anyone explain this? Thanks. R.D.
The loop exits when the condition becomes false. That happens when
len(list) >= 5 (or 6).
Skip
"DataSmash" wrote: I'm confused. Why is it that when I say "while len(list) < 5:", I get 5 items in my list. If I say "while len(list) < 6:", I get 6 items in the list and so on. I would think if I said "less than 5", I would get 4 items.
except that you're saying "as long as there are less than 5 items
in the list, add another one"
</F>
Thanks for explaining and all the additional ideas!
R.D. This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics |
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