Re: make compilation fail

CBFalconer wrote:
> Malcolm wrote:
> > ...
> > It's the other way round. In the olden days, it was sometimes
> > the done thing to call functions without a prototype. It is still
> > possible to do this in some cases for reasons of backwards
> > compatibility, but things have tightened up. Current thinking is
> > that prototypes are desireable and compilers should complain if
> > not given them. Certainly you should always include stdio.h if
> > you
> > wnat to use printf().
>
> Not only should, but must. Using any variadic function without a
> prototype in scope results in undefined behaviour.

You don't _have_ to include <stdio.h> to get a prototype for
printf...

int printf(const char *, ...);

int main(void)
{
printf("%s %s\n", "Hello", "World");
return 0;
}

This is valid in C99 too, even though the first parameter of
printf is normally restrict qualified.

--
Peter

.

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