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Re: Problems using struct pack/unpack in files, and reading them.

From kent nyberg <kent@z-sverige.nu>
Newsgroups comp.lang.python
Subject Re: Problems using struct pack/unpack in files, and reading them.
Date 2015-11-13 16:34 -0500
Message-ID <mailman.309.1447450493.16136.python-list@python.org> (permalink)
References <20151113192045.GA9913@z-sverige.nu> <CALwzidnL1N8efgJfM-EKTgqzmDjg2QwcZVVmDXJB2_QGyFnExA@mail.gmail.com> <20151113201510.GA10107@z-sverige.nu> <mailman.306.1447448484.16136.python-list@python.org> <n25k27$m37$1@reader1.panix.com>

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The main problem was that I forgot to do seek(0).  Thanks alot people.

Though, as many times before, the problem was due to misunderstanding of how python works.
I assumed file.read()[xx:yy] was to be understood as,   in the file, read from index xx to place yy.
That is,  [10:20]  was the same as,   read from 10th char to 20th.  Sort of.


Is it true then to say that every .read  of a file, places an index-offset (?) from where the next read starts?
That is, I need to rewind the file, or else the read will start from where the last read stopped?

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Re: Problems using struct pack/unpack in files, and reading them. Ian Kelly <ian.g.kelly@gmail.com> - 2015-11-13 14:00 -0700
  Re: Problems using struct pack/unpack in files, and reading them. Grant Edwards <invalid@invalid.invalid> - 2015-11-13 21:17 +0000
    Re: Problems using struct pack/unpack in files, and reading them. kent nyberg <kent@z-sverige.nu> - 2015-11-13 16:34 -0500
      Re: Problems using struct pack/unpack in files, and reading them. Grant Edwards <invalid@invalid.invalid> - 2015-11-13 21:44 +0000

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