write binary with struct.pack_into

[Chris Angelico]

On Sat, Oct 6, 2012 at 11:26 PM, Grant Edwards <invalid at invalid.invalid> wrote:
> On 2012-10-06, Dennis Lee Bieber <wlfraed at ix.netcom.com> wrote:
>> On Fri, 5 Oct 2012 20:27:36 -0700 (PDT), palmeira <palmeira at gmail.com>
>> declaimed the following in gmane.comp.python.general:
>>
>>>
>>> #WRITE
>>> fb=open('testOUT.bin')
>>
>>       Unless you specify otherwise, open() defaults to read-only
>
> It also defaults to 'text' mode which does cr/lf translaction.  That
> will break both reads and writes on any binary file containing 0x0a
> and 0x0d bytes.

And, in Python 3, it'll be returning Unicode characters too, unless
the decode fails. You definitely want binary mode.

ChrisA