Re: Python variable assigning problems...

From	Ian Kelly <ian.g.kelly@gmail.com>
Newsgroups	comp.lang.python
Subject	Re: Python variable assigning problems...
Date	2015-12-11 09:36 -0700
Message-ID	<mailman.143.1449851853.12405.python-list@python.org> (permalink)
References	<4b28ee3d-47b3-40ef-b48e-abff720635ed@googlegroups.com> <n4c0of$hqr$1@dont-email.me> <0098ce4a-966b-41df-bf06-352ad451134f@googlegroups.com>

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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.

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Thread

Python variable assigning problems... ICT Ezy <ictezy@gmail.com> - 2015-12-09 09:49 -0800
  Re: Python variable assigning problems... Joel Goldstick <joel.goldstick@gmail.com> - 2015-12-09 12:51 -0500
  Re: Python variable assigning problems... Joel Goldstick <joel.goldstick@gmail.com> - 2015-12-09 12:52 -0500
  Re: Python variable assigning problems... Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-12-09 21:38 +0000
  Re: Python variable assigning problems... Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-12-10 16:33 +1100
  Re: Python variable assigning problems... Denis McMahon <denismfmcmahon@gmail.com> - 2015-12-10 14:03 +0000
    Re: Python variable assigning problems... ICT Ezy <ictezy@gmail.com> - 2015-12-11 08:10 -0800
      Re: Python variable assigning problems... Robin Koch <robin.koch@t-online.de> - 2015-12-11 17:24 +0100
        Re: Python variable assigning problems... Ian Kelly <ian.g.kelly@gmail.com> - 2015-12-11 09:39 -0700
          Re: Python variable assigning problems... Robin Koch <robin.koch@t-online.de> - 2015-12-11 18:52 +0100
            Re: Python variable assigning problems... ICT Ezy <ictezy@gmail.com> - 2015-12-11 10:23 -0800
          Re: Python variable assigning problems... ICT Ezy <ictezy@gmail.com> - 2015-12-11 10:05 -0800
            Re: Python variable assigning problems... Michael Torrie <torriem@gmail.com> - 2015-12-11 11:20 -0700
              Re: Python variable assigning problems... ICT Ezy <ictezy@gmail.com> - 2015-12-11 10:25 -0800
            Re: Python variable assigning problems... Jussi Piitulainen <harvesting@is.invalid> - 2015-12-11 20:27 +0200
              Re: Python variable assigning problems... ICT Ezy <ictezy@gmail.com> - 2015-12-11 10:54 -0800
              Re: Python variable assigning problems... ICT Ezy <ictezy@gmail.com> - 2015-12-11 10:55 -0800
        Re: Python variable assigning problems... ICT Ezy <ictezy@gmail.com> - 2015-12-11 10:00 -0800
          Re: Python variable assigning problems... Michael Torrie <torriem@gmail.com> - 2015-12-11 11:10 -0700
      Re: Python variable assigning problems... Ian Kelly <ian.g.kelly@gmail.com> - 2015-12-11 09:36 -0700

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