list.append problem?

kosh at aesaeion.com kosh at aesaeion.com
Mon Oct 1 23:55:37 CEST 2001


On 1 Oct 2001, newgene wrote:

> I am a newer of python. I have a problem like this code:
>
> >>> a=b=c=[]
> >>> a.append(1)
> >>> b.append(2)
> >>> c.append(3)
> >>> a
> [1, 2, 3]
> >>> b
> [1, 2, 3]
> >>> c
> [1, 2, 3]
>
> a,b,c become the same, although append method applied seperately.
> It's really strange and unreasonable.
> My python is ActivePython Build 210 running on WinNT.

Actually you bound a b and c to the same object. Everything in python is
by reference so you have 3 names for the same object and that is why the
append on any of them showed in all of them since they are really the
same.





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