a problem about "print"

levi nie levinie001 at gmail.com
Wed Jul 4 09:28:17 CEST 2012


Hi,Harrison.
Your method is cool.
But i doubt this, if bList and aList just are attached to the same List
when i write bList=aList,but why the output of the following two code are
different?

code1:
aList=[1,2,3,4,5,6,7,8,9,10]
bList=aList
bList=str(bList)
print aList
print aList[2]

code2:
aList=[1,2,3,4,5,6,7,8,9,10]
aList=str(aList)
print aList
print aList[2]

i'm puzzled now.

2012/7/4 Harrison Morgan <harrison.morgan at gmail.com>

>
>
> On Wed, Jul 4, 2012 at 12:38 AM, levi nie <levinie001 at gmail.com> wrote:
>
>> that's good,thanks.
>> new problem.
>> when i write
>> bList=aList
>> del bList[2]
>> bList and aList both change,how can i make aList not changed?
>>
>>>
>>
> Lists are mutable. That means that when you do bList = aList, you're just
> creating another reference to aList. They both point to the same list, just
> using different names. You should read up a bit on immutable vs. mutable
> objects. Here's something that I found that might explain it a bit better.
> http://henry.precheur.org/python/copy_list
>
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