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From: Ian Kelly <ian.g.kelly@gmail.com>
Newsgroups: comp.lang.python
Subject: Re: Python variable assigning problems...
Date: Fri, 11 Dec 2015 09:36:45 -0700
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On Fri, Dec 11, 2015 at 9:10 AM, ICT Ezy <ictezy@gmail.com> wrote:
> Dear All,
> Very Sorry for the my mistake here. I code here with mu question ...
>
> My Question:
>
> A,B=C,D=10,11
> print(A,B,C,D)
> #(10,11,10,11) --> This is OK!
>
> a=1; b=2
> a,b=b,a
> print(a,b)
> # (1,2) --> This is OK!

This actually results in (2, 1), which is expected; you assign 1 to a
and 2 to b and then swap the values.

> x,y=y,x=2,3
> print(x,y)
> # (3,2) --> Question: How to explain it?
> # Not understand this process. Pl explain ...

The assignments happen from left to right. First, (2,3) is assigned to
(x,y), which has the effect of assigning 2 to x and then 3 to y. Next,
(2,3) is assigned to (y,x), whas the effect of assigning 2 to y and
then 3 to x, overwriting the previous assignments. Then when you do
the print, x has the value 3, and y has the value 2.