Re: function prototype vs function declaration

Ravishankar S wrote:

However it is better to accurately explain the language as it is
formalised rather than as it might be commonly used. Flushing stdin,
voiding main and using gets seem to be distressingly common in real
world usage, but a tutorial that uses them other than to describe their
dangers, would be considered of very low quality.

Point taken. Though this not of the same stature are of writing "void main"
and "fflush(stdin)".

I was thinking that my conclusions are fairly accurate!
But I cannot help but note that what you have mentioned may also be
achieved by using void pointer's.

No. void pointers are quite different from function pointers. Please
read a good textbook before continuing on your tutorial.

Please recommend me a good book, other than K&R which covers these points.
Thank you.

If I am not mistaken a void* must be capabale of storing any pointer
(generic pointer) including
a pointer to a function...

Unfortunately that's not true, and there is a correction for K&R
regarding that. I have a printing of the 2nd edition with that mistake.

"On page 199, beginning of §A6.8, ``Any pointer may be converted to type
void *...'' is changed to ``Any pointer to an object may be converted to
type void *...''." --
http://cm.bell-labs.com/cm/cs/cbook/2ediffs.html

While the C standard is limited in that way, the fact is most popular
systems *do* store function pointers in void *. POSIX is one example,
with regard to the way dlsym works(), and Windows is another.

C isn't very useful without other standards, and some of them conflict.
POSIX for instance makes certain restrictions for pthreads that limit
the optimizations that some compilers may do for C.


George
.

Relevant Pages

  • Re: confusion: casting function pointers
    ... pointer from the 'actual/other modules' that takes arguments of type ... list to types of void *). ... int main{ ... without a prototype, a number of special "promotion" rules take ...
    (comp.lang.c)
  • Re: [RFC] timers, pointers to functions and type safety
    ... * they have callback of type void ... callback is called by the code that even in theory has no ... cast to unsigned long and cast back in the callback. ... number - not a pointer cast to unsigned long, not an index in array, etc. ...
    (Linux-Kernel)
  • Re: Can I Trust Pointer Arithmetic In Re-Allocated Memory?
    ... You can't do pointer arithmetic on a void* value. ... qsort behaves in a manner consistent with its specification. ... actually works as advertised...but doesn't mean that the cast is ...
    (comp.lang.c)
  • Re: The void** pointer breaking symmetry?
    ... void** is a generic pointer type that can be implicitly converted ... because dereferencing the void ** variable once gives ...
    (comp.lang.c)
  • Re: Maps, filters and accumulators
    ... void pointer they get back to a pointer to the appropriate type of data. ... int(*compar)(const void *, const void *)) ... avoid having to do all that work (either by getting a code generator to ...
    (comp.lang.c)