From 6ac06b39b389edca68610cfb42372ae000e514bb Mon Sep 17 00:00:00 2001 From: Guido van Rossum Date: Mon, 21 Sep 1998 14:44:34 +0000 Subject: [PATCH] Patch by Greg Stein to document the 'P' flag. --- Doc/lib/libstruct.tex | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/Doc/lib/libstruct.tex b/Doc/lib/libstruct.tex index be7d80bd0d8..14627b60d6d 100644 --- a/Doc/lib/libstruct.tex +++ b/Doc/lib/libstruct.tex @@ -57,6 +57,7 @@ and Python values should be obvious given their types: \lineiii{d}{double}{float} \lineiii{s}{char[]}{string} \lineiii{p}{char[]}{string} + \lineiii{P}{void *}{integer} \end{tableiii} A format character may be preceded by an integral repeat count; e.g.\ @@ -85,6 +86,15 @@ that exactly enough bytes are used to satisfy the count. For the \character{I} and \character{L} format characters, the return value is a Python long integer. +For the \character{P} format character, the return value is a Python +integer or long integer, depending on the size needed to hold a +pointer when it has been cast to an integer type. A NULL pointer will +always be returned as the Python integer 0. When packing pointer-sized +values, Python integer or long integer objects may be used. For +example, the Alpha and Merced processors use 64-bit pointer values, +meaning a Python long integer will be used to hold the pointer; other +platforms use 32-bit pointers and will use a Python integer. + By default, C numbers are represented in the machine's native format and byte order, and properly aligned by skipping pad bytes if necessary (according to the rules used by the C compiler). @@ -126,6 +136,13 @@ There is no way to indicate non-native byte order (i.e. force byte-swapping); use the appropriate choice of \character{<} or \character{>}. +The \character{P} format character is only available for the native +byte ordering (selected as the default or with the \character{@} byte +order character). The byte order character \character{=} chooses to +use little- or big-endian ordering based on the host system. The +struct module does not interpret this as native ordering, so the +\character{P} format is not available. + Examples (all using native byte order, size and alignment, on a big-endian machine):