[Python-Dev] struct.pack inconsistencies between platforms (original) (raw)

Eli Bendersky eliben at gmail.com
Sun Feb 26 13:34:24 CET 2012

On Sun, Feb 26, 2012 at 12:33, pmon mail <pmon.mail at gmail.com> wrote:

Hi

I have found myself in the following troubling situation. I'm running the following code on a Python 2.6.5 on Linux x86: Python 2.6.5 (r265:79063, Apr 16 2010, 13:09:56) [GCC 4.4.3] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> import struct >>> len(struct.pack('L',0)) 4 Works as expected and documented ( http://docs.python.org/library/struct.html). I'm running the same code on a MacPro (OS X 10.7.3) and I'm getting the following: Python 2.7.1 (r271:86832, Jun 16 2011, 16:59:05) [GCC 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2335.15.00)] on darwin Type "help", "copyright", "credits" or "license" for more information. >>> import struct >>> len(struct.pack('L',0)) 8 Documentation clearly states that the 'L' is a 4 byte integer. Is this a bug? I'm I missing something? By default pack uses native size, not standard size. On a 64-bit machine:

struct.pack('=L', 0) '\x00\x00\x00\x00' struct.pack('L', 0) '\x00\x00\x00\x00\x00\x00\x00\x00' -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://mail.python.org/pipermail/python-dev/attachments/20120226/c0309f5c/attachment.html>

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