🚀 go-pugleaf

tony@online.tmx.com.au (Tony Cook) writes:

>J. Kanze (kanze@gabi-soft.fr) wrote:

>: 	struct X { int i ; char c ; } ;
>: 	X				x ;
>: 	char			c[ 3 ] ;

>: On my system, sizeof( X ) == 8, as does sizeof( x ).  And of course,
>: sizeof( c ) == 3.  Curiously, however, the two variables only take up a
>: total of 8 bytes; in this particular case, the physical sizeof x is 5,
>: and not 8.  This is a perfectly legal, and frequent, implementation.)

>Are you sure about this?  Considering X is a POD, what if the
>programmer has coded:

>	memset(&x, 0, sizeof(X));

>somewhere in their program?  Or does this produce undefined
>behaviour?

I think James meant that only the first 5 bytes of the struct have
meaningful data; the rest is padding needed for alignment. The
compiler must allocate sizeof(X) bytes for any type X, if only
because distinct objects must not overlap.

--
Steve Clamage, stephen.clamage@eng.sun.com

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