Re: programming

["Eric G. Miller" <egm2@jps.net>]

On Mon, 5 Nov 2001 23:34:59 -0500, dman <dsh8290@rit.edu> wrote:

> On Mon, Nov 05, 2001 at 03:42:55PM +0100, martin f krafft wrote:
> | * Erik Steffl <steffl@bigfoot.com> [2001.11.04 17:20:37-0800]:
> | >   not sure if it's clear but there's a difference when sizeof's argument
> | > is array or pointer:
> | 
> | yes. which is exactly why i pointed this out. sizeof is a compile-time
> | function. that's the main point.
> 
> \begin{nitpick}
>     IIRC sizeof() is a macro.  Anyways, C doesn't have inline
>     functions so all funcitons are invoked at runtime.
> \end{nitpick}

<nitpick>C does too have inline functions (C99, that is)</nitpick>

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <math.h>

#ifdef __USE_ISOC99
inline void func(double, double, double *, double *);
#else
void func (double, double, double *, double *);
#endif

void func (double a, double b, double *e, double *inv_f)
{
   assert (a >= b && b > 0);
   *e = sqrt(a*a - b*b) / a;
   *inv_f = a / (a - b);
}

...

int main (int argc, char **argv)
{
  // stuff
  func (a, b, &e, &inv_f);
  // more stuff
}

$ gcc -pg -O2 -Wall -D_ISOC99_SOURCE -o foo foo.c -lm

Will produce a binary with an inlined function (need optimization flag).

-- 
Eric G. Miller <egm2@jps.net>