Thread: gcc warning: implicit declaration of function

Hi all!

This is my first post in here. I disliked C for a long time, but now that I'm getting the hang of it, I like to do stuff with it.

I'm getting a 'Implicit declaration of function' warning. This happens usually when the function that is being called is not defined, nor it's prototype.

make all:

Code:

gcc -ansi -pedantic -Wall -c main.c
main.c: In function 'main':
main.c:4: warning: implicit declaration of function 'newGameArea'
main.c:4: warning: initialization makes pointer from integer without a cast
gcc -ansi -pedantic -Wall -c functions.c
gcc -ansi -pedantic -Wall -c gamearea.c
gcc -ansi -pedantic -Wall -c heightmap.c
gcc -ansi -pedantic -Wall -c position.c
gcc -ansi -pedantic -Wall -c tetromino.c
gcc -o "proj2" main.o functions.o gamearea.o heightmap.o position.o tetromino.o

main.c includes it's own header file, main.h

main.h includes every other header file:

Code:

#pragma once
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "constants.h"
#include "functions.h"
#include "position.h"
#include "tetromino.h"
#include "heightmap.h"
#include "gamearea.h"

main.c (line 4):

Code:

GameArea *gameArea = newGameArea();

The function that is missing, is prototyped on gamearea.h:

Code:

GameArea* newGameArea();

I'm really clueless on what is going on. I'd appreciate some help Thanks!

anatoly

I'm old school, so I never do that kind of thing. On gamearea.h, your prototype should explicitly have parameter of (void):

GameArea* gameArea(void);


Then:
GameArea *gameArea;
//when you're ready to call the function:
gameArea = newGameArea();

I'm not at all familiar with your compiler, but that's how I'd do it.

Hey!

Thanks for the quick replies.

I (probably) accidentally solved it. Not sure what I did. I just closed the IDE in rage, and when I came back and did the makeclean-makeall thing, everything compiled without any errors or warnings.

The target computers (that are going to compile this) are all 'equipped' with the GNU C Compiler, and currently has full support for the "#pragma once" directive. If the need arrises, I'll replace it with "#ifndef"s. I thought the GCC was one of the most popular compilers out there though, but I guess there are some that won't accept "#pragma"

I'll clean up the whole code with your suggestions (use void instead of nothing, use ifndef instead of pragma, and split variable creation from giving it a value) - since I (try to) follow the C programming standards - if I have the time (I need to finish this within 25h 30m - caffeine levels increasing)

Thanks again

- anatoly