14 Nov
2003
14 Nov
'03
6:59 p.m.
struct foo a;
struct foo b;
b = a; /* Legal under ANSI C! */
I could have done:
memcpy(b,a,sizeof(struct foo));
Well, memcpy(&b,&a,sizeof(struct foo)), actually.
I like the first sequence though, since the intent is
a bit more
clear.
It also lets the compiler copy less than the whole struct in some
circumstances - for example, if the struct has holes:
struct foo { char c; int i; };
The compiler would be free to generate the equivalent of
b.c=a.c; b.i=a.i;
rather than the memcpy. Or for
struct foo { int i; char c; };
the compiler might well do the equivalent of memcpy(&b,&a,5) rather
than ...,8 (assuming, for brevity, today's usual 32-bit-cpu sizes, and
the obvious struct-packing conventions).
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