output of the following program. why?

[rishabhagl]

a.c
---

int a;

b.c
---

int a = 10;
main.c
------

extern int a;
int main()
{
        printf("a = %d\n",a);
        return 0;
}

output is :
a = 10

why linking error is not there as 'a' is defined multiple times in a.c and b.c?

[mainframe639]

You are using c?