Re: Possible ANSI C Optimisation Done in Practice?

Hi Chris,


> > #include <string.h>
> > ...
> > for (i = 0; i < strlen(s); i++) {
>
> Excuse my ignorance on this, but how does the compiler know what
> strlen() does? Does an ANSI C compiler *know* that strlen() does not
> have any side-effects, and/or can I not provide my own strlen()
> function in another source file, with very different semantics?


An ANSI C compiler does know the semantics of strlen if the compiler
writers have arranged for that to be the case. For instance, AIX's
<string.h> #defines strlen to be __strlen which the compiler recognises
as *the* standard strlen function.


Yes, you can define your own, although under AIX that would cause some
problems because of the #define. Note though, IIRC ANSI reserves all
function names beginning `str' so you're clashing with them.


Cheers,




Ralph.

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