header file including

head.c:

Code:

---

int add(int a, int b)
{
        return(a+b);
}

---

head.h:

Code:

---

#include <stdio.h>

---

main.c:

Code:

---

#include "head.h"
main()
{
        int a = 10, b = 9;
        printf("addition is : %d", add(a+b));
}

---

=================

Code:

---

cc main.c

---

gives error:

Code:

---

/tmp/ccuq5Rod.o: In function `main':
main.c:(.text+0x28): undefined reference to `add'
collect2: ld returned 1 exit status

---

any line of code needs to be added in any file without changing the file structure/number of files. m unable to make it.

There's nothing wrong with the files and everything wrong with your command line.

Code:

---

cc main.c head.c

---

thanx,
but isn't it possible to change code without changing command line without error?

That is the way you compile programs with multiple source files.

Sure, you can compile everything in a single source, but it's one hell of a hack.