From -7133794129541947396 X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f78e5,444e66e431191b78 X-Google-Attributes: gidf78e5,public X-Google-Thread: 1149ec,c0f8f764e8b7d30f X-Google-Attributes: gid1149ec,public X-Google-ArrivalTime: 1992-12-21 10:52:16 PST Xref: sparky comp.std.c++:1880 comp.std.c:3247 Newsgroups: comp.std.c++,comp.std.c Path: sparky!uunet!haven.umd.edu!decuac!pa.dec.com!e2big.mko.dec.com!jrdzzz.jrd.dec.com!jit533.jit.dec.com!diamond From: diamond@jit533.jit.dec.com (Norman Diamond) Subject: Re: Question about sizeof in C/C++. Message-ID: Sender: usenet@jrd.dec.com (USENET News System) Nntp-Posting-Host: jit533.jit.dec.com Reply-To: diamond@jit.dec.com (Norman Diamond) Organization: Digital Equipment Corporation Japan , Tokyo References: <1992Dec3.195422.26393@cs.brown.edu> <1992Dec07.230924.20465@microsoft.com> Date: Mon, 21 Dec 1992 10:38:23 GMT Lines: 20 In article jamesc@swapsdev.state.state.COM.AU (James Cribb) writes: >Suppose a single struct Something needed 7 bytes of memory. For word >alignment, these might need to start on, say, 4-byte boundaries. >Do the standards guarantee that sizeof(struct Something) will always be >8 rather than 7? Yes. ANSI's original C standard section 3.5.2.1, page 62 lines 2 to 3: "Each non-bit-field member of a structure or union object is aligned in an implementation-defined manner appropriate to its type." Lines 13 to 14: "There may also be unnamed padding at the end of a structure or union, as necessary to achieve the appropriate alignment were the structure or union to be an element of an array." If it is appropriate for a member type to be aligned on a 4-byte boundary, then the implementation-defined manner will result in such alignment, including if necessary a padding byte at the end of the structure. -- Norman Diamond diamond@jit081.enet.dec.com If this were the company's opinion, I wouldn't be allowed to post it. "It's been a lovely recession."