Help with function pointers

[slowpro]

I'm having trouble trying to assess the data members. I tried using -> and . but the compiler keeps saying request for member `magic' in something not a structure or union, etc...

I guess I'm having trouble understanding the concept of function pointers.

 typedef struct _PCB {
   unsigned magic;
   unsigned used;
   unsigned short priority;
   unsigned short state;
   MEM_ADDR esp;
   PROCESS param_proc;
   void* param_data;
   PORT first_port;
   PROCESS next_blocked;
   PROCESS next;
   PROCESS prev;
  char* name;
} PCB;
typedef PCB* PROCESS;

PORT create_process (void (*ptr_to_new_proc) (PROCESS, PARAM),
		     int prio,
		     PARAM param,
		     char *name)
{
   //CAN'T ACCESS THESE DATA MEMBERS
   ptr_to_new_proc->magic	= MAGIC_PCB;
   ptr_to_new_proc->used	= TRUE;
   ptr_to_new_proc->state	= STATE_READY;
   ptr_to_new_proc->priority	= prio;
   ptr_to_new_proc->first_port	= NULL;
   ptr_to_new_proc->name	= name;
   return NULL;
}

[dwks]

What the compiler says makes sense. You can't expect to be able to access members in a function pointer as if it were a structure. It's a function pointer!

What are you trying to do? Are you trying to simply pass a pointer to a structure to that function and then modify the structure? If so, you might try this syntax:

PORT create_process (PROCESS ptr_to_new_proc,
		     int prio,
		     PARAM param,
		     char *name)

[edit] If you want to read up on function pointers, try the tutorial. [/edit]

[Salem]

Because function pointers are meant to be called, not dereferenced.

[dwks]

But when you call it, you dereference it, do you not?

But you can't expect it to act like a pointer to a structure.