From: ad@papyrus.hamburg.com (Andreas Degert) Subject: Re: packed structures 12 Aug 1998 09:37:47 -0700 Message-ID: <87btpqwnr0.fsf.cygnus.gnu-win32@papyrus.hamburg.com> References: <000101bdc547$2b785c20$e645aace@TomStokes> Mime-Version: 1.0 (generated by tm-edit 7.106) Content-Type: text/plain; charset=US-ASCII To: "Tom Stokes" Cc: "CYGWIN32" "Tom Stokes" writes: > The size of this structure is 12 which is wrong. What am I missing? [...] try the following (compile and execute or compile to .s): ------------------------------------------ typedef struct HeaderTag { unsigned long HeaderLength; char PackingType __attribute__ ((packed)); unsigned short NumRows __attribute__ ((packed)); unsigned short PackedSize __attribute__ ((packed)); } __attribute__ ((packed)) HeaderType; #define offset(f) (int)&(((HeaderType*)0)->f) int main(void) { printf("%d,%d,%d,%d\n",offset(PackingType),offset(NumRows), offset(PackedSize),sizeof(HeaderType)); return 0; } -------------------------------------------- Notice the added attribute after the closing brace. Without that the whole structure is padded with 3 additional bytes. ciao Andreas - For help on using this list (especially unsubscribing), send a message to "gnu-win32-request@cygnus.com" with one line of text: "help".