C - Undefined reference to function error with linked files

Question

I started implementing a large program. But I ran into a massive issue. So here is very simplified code of my program. I have a separate .c file for my functions which is normal.c the main program is main.c and I have linked those two with cal.h header file.

main.c

#include <stdio.h>
#include "cal.h"

void main()
{
    int num1, num2, ans;
    num1=5;
    num2=5;
    ans=add(num1, num2);
    printf("%d" ,ans);
}

normal.c

#include "cal.h"

int add(int num1, int num2)
{
    return num1+num2;
}

cal.h

#ifndef CAL_H_INCLUDED
#define CAL_H_INCLUDED
#include <errno.h>

int add(int num1, int num2);

#endif // CAL_H_INCLUDED

but when I compile this, it gives out the error ..\main.c|10|undefined reference to `add'|

I'm using CodeBlocks v.13.12 in Windows 8.1 Any answer for this question is much appreciated. I tried with CodeLite as well, but the same error occurs. Thank you!

Solution

Complete compilation of the code is required in ubuntu terminal use the following

gcc normal.c main.c -o out -lm