how to set pointer to a memory to NULL using memset?

Question

I have a structure

typedef struct my_s {

   int x;
   ...
} my_T;

my_t * p_my_t;

I want to set the address of p_my_t to

Answer 1

Per your update, it seems to me that what you are really trying to do is guard access to a resource, which means you should use a read/write lock that is shared between the processes to guard the ptr to that resource, and test the ptr before using.

• Allocate the structure in shared memory.
• Allocate the ptr to the structure in shared memory.
• Guard access to the ptr to the structure with a Read/Write lock.
• Process A should acquire a WRITE lock to the ptr when initializing or invalidating the ptr and structure.
• Process B should acquire a READ lock to the ptr, and test that the ptr is valid before using the structure