Structures

1. 陣列可存儲一組相同型態的變數；structure 可讓使用自行定義一組包含不同型態的變數的 structure。
   
2. 定義語法
   

   struct [structure tag]
   {
      member definition;
      member definition;
      ...
      member definition;
   } [one or more structure variables];
   

3. 範例：structure 右大括號外，可直接接此 structure 的變數(book)，也可不接變數，在使用時再宣告。
   

   struct Books
   {
      char  title[50];
      char  author[50];
      char  subject[100];
      int   book_id;
   } book;
   

4. 存取範例
   

   #include <stdio.h>
   #include <string.h>
    
   struct Books
   {
      char  title[50];
      char  author[50];
      char  subject[100];
      int   book_id;
   };
    
   int main( )
   {
      struct Books Book1;        /* Declare Book1 of type Book */
      struct Books Book2;        /* Declare Book2 of type Book */
    
      /* book 1 specification */
      strcpy( Book1.title, "C Programming");
      strcpy( Book1.author, "Nuha Ali"); 
      strcpy( Book1.subject, "C Programming Tutorial");
      Book1.book_id = 6495407;
   
      /* book 2 specification */
      strcpy( Book2.title, "Telecom Billing");
      strcpy( Book2.author, "Zara Ali");
      strcpy( Book2.subject, "Telecom Billing Tutorial");
      Book2.book_id = 6495700;
    
      /* print Book1 info */
      printf( "Book 1 title : %s\n", Book1.title);
      printf( "Book 1 author : %s\n", Book1.author);
      printf( "Book 1 subject : %s\n", Book1.subject);
      printf( "Book 1 book_id : %d\n", Book1.book_id);
   
      /* print Book2 info */
      printf( "Book 2 title : %s\n", Book2.title);
      printf( "Book 2 author : %s\n", Book2.author);
      printf( "Book 2 subject : %s\n", Book2.subject);
      printf( "Book 2 book_id : %d\n", Book2.book_id);
   
      return 0;
   }