Question

I am having problem with importing external function to a main c file.

Here is my minimal code:

/* main.c */

#include<stdio.h>
extern int func() 

int main(){
    extern int func();
}

/*external file with one function that I want to     
import*/

#include<stdio.h>

int func(){
    printf("Hello World Again\n");
}

I compile and run like this – gcc main.c and then ./a.out but nothing is happening.
Any idea ?

Answer 1

You have to compile the file containing func also

gcc -Wall main.c external_file.c

(Note that the -Wall in the compiler command isn’t absolutely necessary but is very good practice)

As noted by others, you also need to fix your code to call func rather than just re-declaring it.