k...@aspodata.se writes:
[...]
> To exemplify the "as they are used" statement, take a function pointer
> declaration:
>
> void (*log_func)(int priority, const char *format);
>
> here you cannot conveniently move the "*" to the "void" so it will look
> like a "pointer" declaration; it declares log_func to be something which
> if used as (*log_func)(a, b, d) will "give" you a void value.
Unless something more interesting is being done, function pointers don't
need to be dereferenced, they can be used just like functions. And
vice-versa. Eg, this useless little program converts all its arguments
to ints and prints a message stating if they were odd or even twice:
-------
#include <stdlib.h>
#include <stdio.h>
static void even(int d)
{
printf("%d is even\n", d);
}
static void odd(int d)
{
printf("%d is odd\n", d);
}
static void (*f[])(int) = {
even,
odd
};
int main(int argc, char **argv)
{
int i;
while (*++argv) {
i = atoi(*argv);
/* function name used as expression turns into function pointer */
(i & 1 ? odd : even)(i);
/* function pointer can be used like function */
f[i & 1](i);
}
return 0;
}
------
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