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From: Michael Torrie <torriem@gmail.com>
Newsgroups: comp.lang.python
Subject: Re: Pyhon 2.x or 3.x, which is faster?
Date: Tue, 8 Mar 2016 17:34:59 -0700
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On 03/07/2016 05:45 PM, Chris Angelico wrote:
> On Tue, Mar 8, 2016 at 11:22 AM, BartC <bc@freeuk.com> wrote:
>>
>> (Is a byte string the same as a byte array? Is a byte array the same as an
>> array.array? If I remove this line from my code, where 'data' has just been
>> read from a file:
>>
>>    data=array.array('B',data)
>>
>> then it still works - Python 3. But not on Python 2. If I do .read on a
>> binary file I get a byte string in Python 3, but a string in Python 2. That
>> sort of mess.
> 
> The default string in Py2 *is* a byte string.

There are some interesting differences I found between a Python 2 string
(composed of bytes) and a Python 3 byte string, such as what you'd get
from calling read() on a file handle opened in binary mode.  That is in
Python 2, indexing a string returns a string of length 1.  In Python
3.5, indexing a byte string returns a value, the equivalent of calling
ord() on the single byte string.  This makes it a bit difficult to make
the code easily work between Python 2 and 3 and handle bytes.  Any ideas
there?