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Re: A syntax question

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Date Mon, 10 Nov 2014 09:35:47 -0500
Subject Re: A syntax question
From Joel Goldstick <joel.goldstick@gmail.com>
To Wolfgang Maier <wolfgang.maier@biologie.uni-freiburg.de>
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On Mon, Nov 10, 2014 at 6:39 AM, Wolfgang Maier
<wolfgang.maier@biologie.uni-freiburg.de> wrote:
> You may want to read:
>
> https://docs.python.org/3/faq/programming.html?highlight=global#why-am-i-getting-an-unboundlocalerror-when-the-variable-has-a-value
>
> from the Python docs Programming FAQ section.
> It explains your problem pretty well.
>
> As others have hinted at, always provide concrete Python error messages and
> tracebacks instead of vague descriptions.
>
> Best,
> Wolfgang
>
>
>
> On 11/10/2014 12:07 PM, Mok-Kong Shen wrote:
>>
>>
>> I don't understand the following phenomenon. Could someone kindly
>> explain it? Thanks in advance.
>>
>> M. K. Shen
>>
>> -------------------------------------------------
>>
>> count=5
>>
>> def test():
>>    print(count)
>>    if count==5:
>>      count+=0  ### Error message if this line is active, otherwise ok.
>>      print(count)
>>    return
>>
>> test()
>
>
> --
> https://mail.python.org/mailman/listinfo/python-list

Your problem is that count is not local.  You are reading count from
an outer scope.  When you try to increment count in your function, it
can't because it doesn't exist.
Don't use globals.

-- 
Joel Goldstick
http://joelgoldstick.com

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Thread

A syntax question Mok-Kong Shen <mok-kong.shen@t-online.de> - 2014-11-10 12:07 +0100
  Re: A syntax question alister <alister.nospam.ware@ntlworld.com> - 2014-11-10 11:23 +0000
    Re: A syntax question David Palao <dpalao.python@gmail.com> - 2014-11-10 12:31 +0100
      Re: A syntax question Grant Edwards <invalid@invalid.invalid> - 2014-11-10 14:44 +0000
        Re: A syntax question alister <alister.nospam.ware@ntlworld.com> - 2014-11-10 14:54 +0000
          Re: A syntax question alister <alister.nospam.ware@ntlworld.com> - 2014-11-10 14:56 +0000
            Re: A syntax question Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-11-10 19:53 -0500
              Re: A syntax question alister <alister.nospam.ware@ntlworld.com> - 2014-11-11 09:04 +0000
          Re: A syntax question Grant Edwards <invalid@invalid.invalid> - 2014-11-10 16:11 +0000
            Re: A syntax question Chris Angelico <rosuav@gmail.com> - 2014-11-11 03:18 +1100
              Re: A syntax question Roy Smith <roy@panix.com> - 2014-11-10 14:48 -0500
    Re: A syntax question Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-11-10 20:08 +0000
    Re: A syntax question Tim Chase <python.list@tim.thechases.com> - 2014-11-10 14:29 -0600
  Re: A syntax question Wolfgang Maier <wolfgang.maier@biologie.uni-freiburg.de> - 2014-11-10 12:39 +0100
  Re: A syntax question Joel Goldstick <joel.goldstick@gmail.com> - 2014-11-10 09:35 -0500
  Re: A syntax question Chris Angelico <rosuav@gmail.com> - 2014-11-11 01:54 +1100
  Re: A syntax question Peter Otten <__peter__@web.de> - 2014-11-10 16:10 +0100
  Re: A syntax question Joel Goldstick <joel.goldstick@gmail.com> - 2014-11-10 10:27 -0500

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