[ILUG] gcc compile options

[Lars Hecking]

RenWei writes:
> hi ,
>  i want to know how "align" works in gcc .
> i use this in my program, run in a X86 box, RedHat 6.2 full installed:
> 
> int a __attribute__ ((aligned(8)));
> 
> printf("size of a : %d \n", sizeof(a));
> 
> i want it's size be 8 bytes, by i get 4.

 Four shall be the number of bytes in an int, and the number of bytes
 in an int shall be four. Five shall it not be, neither three. Six is
 right out.[1]

 All for x86, of course.

 However, above code will align 'a' on a 8-byte boundary.

> anyone can tell me how to use align in detail?

 The gcc info manual, section "C extensions", subsection "Type Attributes".

[1] With humble apologies to the authors of the Book of Armaments.