Path: csiph.com!usenet.pasdenom.info!gegeweb.org!de-l.enfer-du-nord.net!feeder1.enfer-du-nord.net!feeds.phibee-telecom.net!newsfeed.xs4all.nl!newsfeed6.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.007 X-Spam-Evidence: '*H*': 0.99; '*S*': 0.00; 'subject:: [': 0.03; 'parameter': 0.07; 'subject:question': 0.08; 'str,': 0.09; 'cc:addr:python-list': 0.10; 'def': 0.10; 'anyway': 0.11; 'advance.': 0.15; '"+="': 0.16; 'subject:] ': 0.19; 'earlier': 0.21; 'x-mailer:apple mail (2.1084)': 0.22; 'cc:2**0': 0.23; 'seems': 0.23; 'cc:no real name:2**0': 0.24; 'cc:addr:python.org': 0.25; 'header:In-Reply-To:1': 0.25; 'question': 0.27; "doesn't": 0.28; 'lines': 0.28; 'prints': 0.29; 'str': 0.29; 'url:mailman': 0.29; 'function': 0.30; 'url:python': 0.32; 'subject:lists': 0.32; 'url:listinfo': 0.32; 'function.': 0.33; "can't": 0.34; 'skip:- 50': 0.34; 'received:google.com': 0.34; 'thanks': 0.34; 'similar': 0.35; 'received:209.85': 0.35; 'list.': 0.35; 'message- id:@gmail.com': 0.36; 'url:org': 0.36; 'should': 0.36; 'two': 0.37; 'why': 0.37; 'received:209': 0.37; 'header:Received:5': 0.40; 'help': 0.40; 'url:mail': 0.40; 'your': 0.60; 'header :Message-Id:1': 0.62; 'manner': 0.74; 'received:ru': 0.81 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=subject:mime-version:content-type:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to:x-mailer; bh=n04+e30Rht05Cti+uGkbJr4QrZM4yJboevfitSL+jcU=; b=eXkkvlYkLCZoHZBpyAa5zAIpaYE/jA7hc3l5dXVPU6S1bxCCgLKbQe6T1b9Ejo/b49 GLd9lCvFR0iokTP/a6KsbI1FsoUqDSKWXhi5jQGYFNToW9P8VBaGRYL4lHumPXZVzdcu 4brky358nqA79ARiudA4hXUsXbFtU8UvR3BRhpq4QR+IkZMFYpM0FgAXaRXRH1iB1XdZ EU51KhZp81SpriWNk0UVniMShRCrywqAKUDn1OR7d5UZq3AHAww8IS2xlX3KnKdXNBi4 JoaqncTznIjrp5RsD0Ktk2hvTAAHxxZ04gW0z5oSTHhxYdFapmiw8bgfH9XC1n7Vrbl7 NjPA== Subject: Re: [newbie] A question about lists and strings Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: text/plain; charset=koi8-r From: Roman Vashkevich In-Reply-To: Date: Fri, 10 Aug 2012 13:28:57 +0400 Content-Transfer-Encoding: quoted-printable References: To: Mok-Kong Shen X-Mailer: Apple Mail (2.1084) Cc: python-list@python.org X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Newsgroups: comp.lang.python Message-ID: Lines: 41 NNTP-Posting-Host: 2001:888:2000:d::a6 X-Trace: 1344590943 news.xs4all.nl 6940 [2001:888:2000:d::a6]:52915 X-Complaints-To: abuse@xs4all.nl Xref: csiph.com comp.lang.python:26849 10.08.2012, =D7 13:19, Mok-Kong Shen =CE=C1=D0=C9=D3=C1=CC(=C1): >=20 > In an earlier question about lists, I was told about the issue of > creation of local names in a function. However, I still can't > understand why the program below outputs: >=20 > [999] sss > [999] >=20 > and not two identical lines of output. For both operators "+=3D" = should > anyway work in similar manner in the function xx in my view. >=20 > Thanks for your help in advance. >=20 > M. K. Shen >=20 > ---------------------------------------------------------- >=20 > def xx(list,str): > list+=3D[999] > str+=3D"sss" >=20 > lista=3D[] > stra=3D"" > lista+=3D[999] > stra+=3D"sss" > print(lista,stra) >=20 > listb=3D[] > strb=3D"" > xx(listb,strb) > print(listb,strb) > --=20 > http://mail.python.org/mailman/listinfo/python-list It seems like your xx() function doesn't return local str parameter and = prints the global empty str, whereas it mutates the global list. Roman=