Hi Darin,

    Lovely to hear from you again!

 > #include 

 > typedef struct moo {
 >     int i;
 >     char c;
 > } moo;

 > int main()
 > {
 >     printf("sizeof(moo) * 100 = %d\nsizeof(moo[100]) =
 > %d\n",
 >            sizeof(moo) * 100, sizeof(moo[100]));
 >     exit(0);
 > }

 > [0] f:\tmp\a>gcc a.c -o a.exe

 > [0] f:\tmp\a>a.exe
 > sizeof(moo) * 100 = 800
 > sizeof(moo[100]) = 800

 >>> in other words does sizeof() include any slack space
 >>> required for
 >>> alignment.

 > I'm not sure if there is any requirement on the
 > compiler to do this.  In fact, I would doubt it.  Some
 > platforms may decide to use that slack space for other
 > things if there is no performance impact.  Or if you
 > give it a pragma.  For example, with EMX (GCC for OS/
 > 2), if I add #pragma pack(1), I get an output of 500
 > for both.

 >  BB>     Sizeof() returns the actual number of bytes of the dingus in the
 >  BB> brackets. Sizeof(moo) * 100 should return 300 with byte alignment.

 > Nope - with 16-bit ints, it would probably return 400
 > with byte alignment ;-)

    With pragma pack 1 on the MSC V10 compiler it actually did return 300.
It had to or the data file wouldn't work at all :-)

 >  BB> The sizeof(an array of 100 structures of type moo) would also depend
 >  BB> on alignment. However unless you change alignment within the program
 >  BB> they should be the same.

 > Somehow, my copy of the ANSI C standard eludes me, so
 > I can't even look this up.  I suspect it's correct,
 > but can't confirm... :-/

    I ran almost the identical program you typed in above on MSVC (on the
laptop), and the results were exactly the same, but like you I am not sure
compilers *must*. The only difference in the program snippets was that I
used two separate printf() statements. :-)

 >  BB>     Darin McBride should be able to answer this off the top of his
 >  BB> head.

 > A bit much confidence, methinks.  ;-)

    Darin if you don't know, there are few do. Reminds me of that old piece
of British doggerel:-

    "The Duke of Buccleugh
    didn't like whale steugh
    but there are feugh
    wheugh deugh!
    deugh yeugh?"

Best Wishes,
Bill.

---