warn01.c

gcc-you can use this code to learn something about gcc, and inquire further into linux,

// Build don't link:
// Special g++ Options: -W -Wall

typedef unsigned long size_t;
extern void* malloc (size_t);
extern void free (void*);
extern void* realloc (void*, size_t);

struct vtable {
  void* (* _malloc) (size_t);
  void (* _free) (void*);
  void* (* _realloc) (void*, size_t);
};

struct vtable mtable = { malloc, free };  // WARNING - _realloc