On Wed, 11 Jun 2014 21:56:06 -0700, hito koto wrote:
> I want to use while statement,
>
> for example:
>>>> def foo(x):
> ... y = []
> ... while x !=[]:
> ... y.append(x.pop())
> ... return y
> ...
>>>> print foo(a)
> [[10], [5, 6, 7, 8, 9], [1, 2, 3, 4]]
>>>> a
> [] but this is empty
>>>> so,I want to leave a number of previous (a = [[1, 2, 3, 4],[5, 6, 7,
>>>> 8, 9],[10]])
I wouldn't use a while statement. The easy way is:
py> a = [[1, 2, 3, 4],[5, 6, 7, 8, 9],[10]]
py> y = a[::-1]
py> print y
[[10], [5, 6, 7, 8, 9], [1, 2, 3, 4]]
py> print a
[[1, 2, 3, 4], [5, 6, 7, 8, 9], [10]]
If you MUST use a while loop, then you need something like this:
def foo(x):
y = []
index = 0
while index < len(x):
y.append(x[i])
i += 1
return y
This does not copy in reverse order. To make it copy in reverse order,
index should start at len(x) - 1 and end at 0.
--
Steven
--
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