Implicit Declaration Of Function

[nathanpc]

Hello,
I've just organized my code by using headers, but just as I've done this, I got a warning that turned into an error when linking.

I have a code(use of a function that is inside a header) in test.c that is like this:

#include "test1.h"

/* Some code */
main()
{
   Testing();
}

And my test1.h header is like this:

void Testing();
void print(int, int, int, const char*);

And at test1.c

void Testing()
{
   print(0xF9, 27, 5, "\xC9\\xBB");
}

void print(int colour, int x, int y, const char *string)
{
   volatile char *video=(volatile char*)0xB8000 + y*160 + x*2;
   while(*string != 0)
   {
      *video=*string;
      string++;
      video++;
      *video=colour;
      video++;
   }
}

When I try to compile the code, I got this:

ubuntu@eeepc:~/Development/Test$ gcc -o test.o -c test.c -Wall -Wextra -nostdlib -nostartfiles -nodefaultlibs
test.c: In function ‘main’:
test.c:11: warning: implicit declaration of function ‘Testing’
ubuntu@eeepc:~/Development/Test$

At the time it's just a simple warning, but when I try to link it...

ubuntu@eeepc:~/Development/Test$ ld -T linker.ld -o kernel.bin loader.o test.o
test.o: In function main':
test.c:(.text+0xfc): undefined reference toTesting'

What I need to do?

Best Regards,
Nathan Paulino Campos

[MK27]

What I need to do?

What do you want to do?

Just combine test.h into test1.c and compile like this:

gcc -o myprog test.c test1.c