Thread: global variable question?

File a.c

Code:

int a = 5;

file b.c

Code:

#include <stdio.h>int main()
{
    printf("%d", a);
    return 0;
}

My understanding was that if a file is within a project (a.c) and a variable was declared outside the scope of any of the functions within that file that that variable would be global....Am I incorrect here?

Certainly when I place

Code:

extern int a;

before main the code compiles

Is there no such thing as a global variable that crosses file boundaries?
Thanks