Author: Dave Gomboc
Date: 05:47:23 01/02/03
Go up one level in this thread
On January 01, 2003 at 11:50:58, Lieven Clarisse wrote:
[snip]
>I know for instance that:
>
>ptr=&R[i];
>if((*ptr==3)||(*ptr==7)) {;}
>
>is faster then:
>
>if((R[i]==3)||(R[i]==7)) {;}
That isn't necessarily true. It depends on the instruction set (and the
compiler, of course).
I'd write this as:
const int temp = R[i];
if ((3 != temp) || (7 != temp)) { ... };
That way, a dumb compiler will still do the memory access only once, in the most
natural way for the native instruction set.
(I don't put the ints first for optimization, I put the ints first so if I
mistype (3 == temp) as (3 = temp) I get a compile-time error. :-)
Dave
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