Article View: comp.std.c
Article #2016Wanted: struct's address from member's address please.
From: Ronald S H Khoo
Date: Fri, 23 Nov 1990 09:34
Date: Fri, 23 Nov 1990 09:34
27 lines
1194 bytes
1194 bytes
Can someone give me a pointer to relevant bits of the Standard please ?
I'd like to know if
1) I can have a strictly conforming portable function that returns
the address of a structure, given the address of a member of
said structure,
2) Is this function the one I want ? (and is it strictly conforming?)
#include <stddef.h>
/* typedefs to define type1 and type2 */
struct foo {
type1 first_bit;
type2 second_bit;
};
struct foo *
func(type2 *arg)
{
return (struct foo *) ((char *)arg -
offsetof(struct foo, second_bit));
}
--
ronald@robobar.co.uk +44 81 991 1142 (O) +44 71 229 7741 (H)
Technical Details
Message-ID:
<1990Nov23.093458.24957@robobar.co.uk>Path:
arc1-ca.pugleaf.net!utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!rutgers!sun-barr!cs.utexas.edu!samsung!dali.cs.montana.edu!uakari.primate.wisc.edu!zaphod.mps.ohio-state.edu!usc!snorkelwacker.mit.edu!bloom-beacon!eru!hagbard!sunic!mcsun!ukc!stl!robobar!ronaldShow Full Headers
Complete Article Headers
Path: arc1-ca.pugleaf.net!utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!rutgers!sun-barr!cs.utexas.edu!samsung!dali.cs.montana.edu!uakari.primate.wisc.edu!zaphod.mps.ohio-state.edu!usc!snorkelwacker.mit.edu!bloom-beacon!eru!hagbard!sunic!mcsun!ukc!stl!robobar!ronald From: ronald@robobar.co.uk (Ronald S H Khoo) Newsgroups: comp.std.c Subject: Wanted: struct's address from member's address please. Message-ID: <1990Nov23.093458.24957@robobar.co.uk> Date: 23 Nov 90 09:34:58 GMT Organization: Robobar Ltd., Perivale, Middx., ENGLAND. Lines: 27