struct product {
int weight;
float price;
} ;

product apple;
product banana, melon;

struct product {
int weight;
float price;
} apple, banana, melon;

// example about structures
#include <iostream>
#include <string>
#include <sstream>
using namespace std;

struct movies_t {
string title;
int year;
} mine, yours;

void printmovie (movies_t movie);

int main ()
{
string mystr;

  mine.title = "2001 A Space Odyssey";
  mine.year = 1968;

  cout << "Enter title: ";
  getline (cin,yours.title);
  cout << "Enter year: ";
  getline (cin,mystr);
  stringstream(mystr) >> yours.year;

  cout << "My favorite movie is:\n ";
  printmovie (mine);
  cout << "And yours is:\n ";
  printmovie (yours);
return 0;
}

void printmovie (movies_t movie)
{
  cout << movie.title;
  cout << " (" << movie.year << ")\n";
}

struct movies_t {
string title;
int year;
};

movies_t amovie;
movies_t * pmovie;
pmovie = &amovie;

// pointers to structures
#include <iostream>
#include <string>
#include <sstream>
using namespace std;

struct movies_t {
string title;
int year;
};

int main ()
{
string mystr;

  movies_t amovie;
  movies_t * pmovie;
  pmovie = &amovie;

  cout << "Enter title: ";
  getline (cin, pmovie->title);
  cout << "Enter year: ";
  getline (cin, mystr);
  (stringstream) mystr >> pmovie->year;

  cout << "\nYou have entered:\n";
  cout << pmovie->title;
  cout << " (" << pmovie->year << ")\n";

return 0;
}

struct movies_t {
string title;
int year;
};

struct friends_t {
string name;
string email;
  movies_t favorite_movie;
  } charlie, maria;

friends_t * pfriends = &charlie;

charlie.name
maria.favorite_movie.title
charlie.favorite_movie.year
pfriends->favorite_movie.year

union union_name {
  member_type1 member_name1;
  member_type2 member_name2;
  member_type3 member_name3;
  .
  .
} object_names;

union mytypes_t {
char c;
int i;
float f;
  } mytypes;

struct {
char title[50];
char author[50];
  union {
float dollars;
int yen;
  } price;
} book;

struct {
char title[50];
char author[50];
  union {
float dollars;
int yen;
  };
} book;

book.price.dollars
book.price.yen

book.dollars
book.yen

enum Week {SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY};

 enum Week {MONDAY = 1,TUESDAY,WEDNESDAY,THURSDAY,FRIDAY,SATURDAY,SUNDAY};

Week today = TUESDAY;

TUESDAY = 10; //错误！我们不能改变一个枚举值的数值。