On 05/23/2014 11:06 AM, Sivaprasad wrote:
> I have a confusion about structure size calculation.
>
> I have tried to compared structure size result with
> gcc version 4.7.2 20121109 (Red Hat 4.7.2-8) generates code for x86 machine
> and
> cross compiler with gcc version 4.3.4 generate code for custom processor.
>
> struct sample
> {
> short int s;
> }a;
>
> sizeof(a) showing 2 bytes with x86 gcc and 4 bytes with cross compiler.
>
> struct sample
> {
> int i;
> short int s;
> }a;
>
> sizeof(a) showing 8 bytes with x86 gcc and 8 bytes with cross compiler.
>
> When compiler will add hole at end of the structure ?
> why cross compiler trying to make structure size multiple of 4 ?
Because the structure is aligned according to the alignment of its largest
member. In this case the largest alignment is 4. You can use the
packed attribute to change this.
Andrew.
