Question

I have a code like this:

#include<stdio.h>
int main()
{
    extern int i;
    i = 20;
    printf("%d\n", sizeof(i));
    return 0;
}

I get an error like this:

In function `main':
undefined reference to `i'

Even though I have defined i why there is an error thrown?
Thanks in advance.

Answer 1

You have declared i to be defined in a separate file, but haven’t linked to an external file.

If you remove the extern keyword, this will work as you expect.