How to write partial of a buffer which was returned from a C function to a file?

jfong at ms4.hinet.net jfong at ms4.hinet.net
Thu Apr 12 02:20:14 EDT 2018


Chris Angelico於 2018年4月12日星期四 UTC+8下午1時31分35秒寫道:
> On Thu, Apr 12, 2018 at 2:16 PM,  <jfong at ms4.hinet.net> wrote:
> > This C function returns a buffer which I declared it as a ctypes.c_char_p. The buffer has size 0x10000 bytes long and the valid data may vary from a few bytes to the whole size.
> >
> > In every call I know how much the valid data size is, but I suppose I can't use slice to get it because there may be zero byte in it. What to do?
> >
> 
> You suppose? Or have you tested it?
> 
> ChrisA

Yes, I had test it once before. Now, I re-do it again to make sure. After a call which returns 3 bytes of data, I use len(buf) to check the length and get the number 24. I can see the first 24 bytes of data by using buf[:30] but buf[24] will cause an "index out of range" error. I don't know how to see what the buf[24] exactly is but I suppose it might be a zero byte.

--Jach


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