with ctypes, how to parse a multi-string

[Eric]

On May 31, 2:52 pm, Thomas Heller <thel... at ctypes.org> wrote:
> Eric schrieb:
>
>
>
> > Hi,
>
> > I am currently dealing with ctypes, interfacing with winscard libbrary
> > (for smart card access).
>
> > Several APIs (e.g. SCardListReaderGroupsW ) take a pointer to an
> > unicode string as a parameter , which points at function return to a
> > "sequence" of unicode strings, NULL terminated. The last string is
> > double NULL terminated. (of course buffer length is also returned as
> > another parameter).
>
> > e.g. it could return something like
> > 'group1\x00group2\x00group3\x00\x00'
>
> > What should I use as argtypes to my function prototype in order to
> > gain access to the full list? using c_wchar_p works, but it resolves
> > the string until it reaches the first \x00, resulting in having access
> > to the first entry of the list only.
>
> A c_wchar_p instance represent a (one!) zero-terminated string, as you
> already know.  A POINTER(c_wchar) instance is more flexible, you should
> use that instead.  It can be indexed/sliced with arbitrary indexes.
>
> Here is a simple script to get you started:
>
> """
> from ctypes import *
>
> # Normally, the function call will fill the buffer:
> buf = create_unicode_buffer("first\0second\0third\0")
>
> # The pointer you will pass to the function call
> ptr = cast(buf, POINTER(c_wchar))
>
> # function call omitted
>
> # Print the raw result
> print ptr[:len(buf)]
>
> # Print a list of strings
> print ptr[:len(buf)].split("\0")
> """
>
> Thomas

Thanks Thomas, it works as expected!

Regards,

Eric