incompatible implicit declaration

[Jonathan Wakely]

On 27 December 2010 06:18, ali hagigat wrote:
> No Bill, i do not include stdio.h on purpose!

That is your mistake.

> My program is exactly as follows:
> main(){
>        printf("kkkkkkkk=\n");
> }
> and I compile it as:
> gcc -o prog1 prog1.c
> prog1.c: In function ‘main’:
> prog1.c:2: warning: incompatible implicit declaration of built-in
> function ‘printf’
>
> I could not get my answer by google. I guess that printf is a built-in

printf is declared in <stdio.h>

> function and has a function prototype and probably the built-in
> version is being used here. So why implicit declaration? and how it is
>  incompatible?

If you do not declare a function in C then an implicit declaration is
used, see the FAQ I sent you.

The implicit declaration is not compatible with the corret declaration
of printf in <stdio.h>

> Is there a complete list of GCC error and warning messages (and their causes)?

No, but this one is easy, you need to include <stdio.h>