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const char *p;
void dont_do_this(void) {
  const char c_str[] = "This will change";
  p = c_str; /* Dangerous */
  /* ... */
}

void innocuous(void) {
  const char c_str[] = "Surprise, surprise";
}

int main(void) {
  dont_do_this();
  innocuous();  /* p might be pointing to "Surprise, surprise". */

  return 0;
}

void this_is_OK(void) {
  const char c_str[] = "Everything OK";
  const char *p = c_str;
  /* ... */
}
/* p is inaccessible outside the scope of string c_str. */

void squirrel_away(char **ptr_param) {
  char local[10];
  /* Initialize array */
  *ptr_param = local;
}

void rodent() {
  char *ptr;
  squirrel_away(&ptr);
  /* ptr is live but invalid here. */
}

char local[10];
 
void squirrel_away(char **ptr_param) {
  /* Initialize array */
  *ptr_param = local;
}

void rodent() {
  char *ptr;
  squirrel_away(&ptr);
  /* ptr is live and valid here. */
}