How to save a binary file?

Chris Rebert clp2 at rebertia.com
Wed Oct 6 07:01:12 CEST 2010


> On Oct 5, 2010 8:03pm, MRAB <python at mrabarnett.plus.com> wrote:
>> On 05/10/2010 23:50, hidura at gmail.com wrote:
>> I did but the mistake is: Error interpreting JPEG image file (Not a JPEG
>> file: starts with 0x5c 0x6e)
>>
>> I think the problem is maybe in the binary code here is:
<snip>
>>  > On Oct 5, 2010 6:18pm, "Jonas H." jonas at lophus.org> wrote:
>>  > > On 10/05/2010 11:11 PM, hidura at gmail.com wrote:
>>  > > Hello, how i can save a binary file, i read in the manual in the IO
>> area
>>  > > but doesn' t show how to save it.
>>
>>  > > Here is the code what i am using:
>>  > > s = open('/home/hidura/test.jpeg', 'wb')
>>  > > s.write(str.encode(formFields[5]))
>>  > > s.close()
<snip>
>> Why are you encoding it? A JPEG file should contain the binary data,
>> not a textual encoding of its bytes. The error message you got said
>> that the contents of the file started with a backslash.
>>
>> If you print out, say, repr(str[ : 10]) you should get something like
>>
>> 'ÿØÿà\x00\x10JFIF'.
>>
>> Try this instead:
>>
>> s = open('/home/hidura/test.jpeg', 'wb')
>> s.write(str)
>> s.close()
>>
>> Incidentally, 'str' is a bad name for a variable because it's the name
>> of the built-in string type.

On Tue, Oct 5, 2010 at 9:53 PM,  <hidura at gmail.com> wrote:
> I has to use repr to convert in this string: ÿØÿà\x00\x10JFIF?

No, you don't/shouldn't convert it at all. Read/use the 3 lines of
suggested code that MRAB gave:
s = open('/home/hidura/test.jpeg', 'wb')
s.write(str)
s.close()

Cheers,
Chris



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