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


int main(int argc, char ** argv) {
  struct date {short day, month, year;};

  typedef struct date Date;
  typedef struct date * Datep;

  // create date using struct date 
  struct date today = {6,2,2017};	
  printf("today: %02d/%02d/%04d\n", today.month, today.day, today.year);

  // create date using typedef
  Date tomorrow = {7,2,2017};	
  printf("tomorrow: %02d/%02d/%04d\n", tomorrow.month, tomorrow.day, tomorrow.year);

  // create date pointer to existing date
  Datep todayp = &today;
  printf("todayp: %02d/%02d/%04d\n", todayp->month, todayp->day, todayp->year);


  // create new date using pointer to allocated memory
  Datep yesterday = malloc(sizeof(Datep));
  yesterday->month = 2;
  yesterday->day = 5;
  yesterday->year = 2017;
  printf("yesterday: %02d/%02d/%04d\n", yesterday->month, yesterday->day, yesterday->year);
  
  Date nextyear = today;
  nextyear.year = 2018;
  printf("nextyear: %02d/%02d/%04d\n", nextyear.month, nextyear.day, nextyear.year);
  printf("today: %02d/%02d/%04d\n", today.month, today.day, today.year);

  // create a date with just the first two values specified
  Date birthday = {5, 2};
  printf("birthday: %02d/%02d/%04d\n", birthday.month, birthday.day, birthday.year);

  // create a date with just the last value specified
  Date graduation = {.year = 2017};
  printf("graduation: %02d/%02d/%04d\n", graduation.month, graduation.day, graduation.year);


  // create a recursive data structure
  typedef struct person {
    char * first;
    char * last;
    Date birthday;
    struct person * friend;
  } Person;


  // create and initialize a person
  Person john = { "John", "Smith", { 4, 7, 1776 }};
  printf("john: %s %s, %02d/%02d/%04d\n", john.first, john.last,
	 john.birthday.month, john.birthday.day, john.birthday.year);

  // create and initialize a person with a friend
  Person mary = { "Mary", "Johnson", { 4, 7, 1776 }, &john};
  printf("mary: %s %s, %02d/%02d/%04d\n", mary.first, mary.last,
	 mary.birthday.month, mary.birthday.day, mary.birthday.year);
  printf("mary's friend: %p %s\n", mary.friend, mary.friend->first);

  // create a pointer to a person
  Person * jane = malloc(sizeof(Person));
  char * f = "Jane";
  char * l = "Doe";
  Date d = {5, 6, 1999};
  jane->first = f;
  jane->last = l;
  jane->birthday = d;
  printf("jane: %s %s, %02d/%02d/%04d\n", jane->first, jane->last,
	 jane->birthday.month, jane->birthday.day, jane->birthday.year);

  // comment these out and run valgrind
  free(yesterday);
  free(jane);
}