Extracting a short using struct - won't print.
Graham Nicholls
graham at rockcons.co.uk
Thu Aug 7 12:00:29 EDT 2003
Peter Hansen wrote:
> Graham Nicholls wrote:
>>
>> Thanks to Richard and Alex, I'm doing this:
>>
>> seg_stru=">BHH"
>> seg_data=self.fhand.read(struct.calcsize(seg_stru))
>> data=struct.unpack(seg_stru,seg_data)
>> x=seg_data[1]
>> y=seg_data[2]
>
> Why are you unpacking the struct if you aren't going to use the
> unpacked data?
Err, I'm trying to extract two shorts - the x and y size in pixels of an
image, which I'll use to scale it to fit another pair of parameters. What
makes you think I'm not using the data? Am I not - I thought I was!
I realise that ">BHH" above ouhjt really to be "xHH" but aside from that, I
don't understand your point - theres more code after the debug in the rel
app - returning x and y.
>
>> if debug:
>> print ("DEBUG: Image [%s] is [%d] by [%d] pixels" %
>> (self.fname,x,y))
>
> Best way to troubleshoot this kind of thing, in my experience,
> is to insert "import pdb; pdb.set_trace()" into the code just
> above the failing line, then use the debugger to inspect the
> values directly just before they are used. (You need to execute
> the "r" or "return" command immediately after the debugger is
> entered... the rest is pretty straightforward to learn.)
>
I'll give that a go, thanks
> -Peter
--
Graham Nicholls
Rock Computer Consultancy
More information about the Python-list
mailing list