悬挂指针

Example:

{
  char *dp = NULL;
  /* ... */
  {
      char c;
      dp = &c;
  } /* c falls out of scope */
    /* dp is now a dangling pointer */
}

#include 
void func()
{
   char *dp = malloc(A_CONST);
   /* ... */
   free(dp);         /* dp now becomes a dangling pointer */
   dp = NULL;        /* dp is no longer dangling */
   /* ... */
}

int *func(void)
{
   int num = 1234;
   /* ... */
   return #
}

int f(int i)
{
   char *dp;    /* dp is a wild pointer */
   static char *scp;  /* scp is not a wild pointer:
                       * static variables are initialized to 0
                       * at start and retain their values from
                       * the last call afterwards.
                       * Using this feature may be considered bad
                       * style if not commented */
}