example c code to test out double pointer cleaningup

doubleptr_cleanup.c

#include <stdio.h>
#include <stdlib.h>

typedef struct 
{
  int val;
} MyStruct;

void cleanup(MyStruct** s)
{
  if (s != NULL)
  {
    printf("struct's value is %d\n", (*s)->val);
    free(*s);

    *s = NULL;
  }
}

int main(void)
{
  MyStruct* s = malloc(sizeof(MyStruct));
  s->val = 10; 

  cleanup(&s);

  // this should equal null
  if (s == NULL)
  {
    printf("OK\n");
  }
  return 0;
}