Terry Reedy wrote:
> "Sergey Dorofeev" <[EMAIL PROTECTED]> wrote in message
> news:[EMAIL PROTECTED]
>
>>I can use string.unpack if string in struct uses fixed amount of bytes.
>
>
> I presume you mean struct.unpack(format, string). The string len must be
> known when you call, but need not be fixed across multiple calls with
> different strings.
>
>
>>But is there some extension to struct modue, which allows to unpack
>>zero-terminated string, size of which is unknown?
>>E.g. such struct: long, long, some bytes (string), zero, short,
>>short,short.
> Size is easy to determine. Given the above and string s (untested code):
> prelen = struct.calcsize('2l')
> strlen = s.find('\0', prelen) - prelen
> format = '2l %ds h c 3h' % strlen # c swallows null byte
shouldn't this be '2l %ds c 3h'??
>
> Note that C structs can have only one variable-sized field and only at the
> end. With that restriction, one could slice and unpack the fixed stuff and
> then directly slice out the end string. (Again, untested)
>
> format = 2l 3h' # for instance
> prelen = struct.calcsize(format)
> tup = struct.unpack(format, s[:prelen])
> varstr = s[prelen, -1] # -1 chops off null byte
Perhaps you meant varstr = s[prelen:-1]
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