Question

So i have two structs in the global section

typedef struct stack_1
 {
  short ctr;
 } stack_1;

typedef struct stack_2
 {
   struct stack_1 *s1;
 } stack_2;

then later in the code i do

struct stack_2 *x; 

what is my x initialized to ?? 0 or Null. Thank you in advance.

Answer 1

If your declaration is outside any function or with the static keyword (more precisely, has static storage duration), the initial value of x is a null pointer (which may be written either as 0 or as NULL). If it’s inside a function and not defined as static (i.e., has automatic storage duration), its initial value is garbage.