Pointer-array-extern question

Question

File 1.c

int a[10];

File main.c:

extern int *a;

int main()
{
    printf(\"%d\\n\", a[0])         


        

Answer 1

Check out the output of the following code.

File1.c

#include 

extern int* my_arr;

void my_print()
{
  printf("%d", my_arr);
}

main.c

#include 

int my_arr[2] = {1,2};

extern void my_print();

void main()
{
    my_print();
}

output

1

inside File1.c my_arr is a pointer variable that has the value of 1. meaning the 1st element of my_arr[] was assigned to it. Then if you use *my_arr to access memory location ox1, you get seg fault because you are not allowed to access ox01.

Why my_arr pointer was assigned 1 (the first element of my_arr[])?

Has to do with how assembler works. Read this article

Why your code can't access 0x01 ?

I know it has to do with the operating system not allowing some address space to be accessed by user code. Thats all I know. google it if you want more info.