函式傳入結構內容

1. 承上例，將列印 struct Books 的 title, author, book_id 部分，寫成函式 printBook。

   [dywang@deyu zzz]$ cat struct2.c
   #include <stdio.h>
   #include <string.h>
   
   struct Books {
   	char  title[50];
   	char  author[50];
   	int   book_id;
   };
   
   void printBook( struct Books book ) {
   	printf( "book.title : %s\n", book.title);
   	printf( "book.author : %s\n", book.author);
   	printf( "book.book_id : %d\n", book.book_id);
   	book.book_id = 999999;
   }
   
   int main () {
   	struct Books book1;
   	struct Books book2;
    
   	strcpy( book1.title, "RHCSA");
   	strcpy( book1.author, "dywang"); 
   	book1.book_id = 123456;
   
   	strcpy( book2.title, "Python");
   	strcpy( book2.author, "Linda");
   	book2.book_id = 123321;
    
   	printBook( book1 );
   	printf( "book1_id : %d\n", book1.book_id);
   	printBook( book2 );
   	printf( "book2_id : %d\n", book2.book_id);
   
   	return 0;
   }
   

2. 編譯

   [dywang@deyu zzz]$ gcc -o struct2 struct2.c
   

3. 執行結果：呼叫函式 printBook 是複製 struct 的內容傳入，所以函式 printBook 列印後，設定 book_id=999999，退出函式後再列印 bbok1.book_id 還是 123456，book2.book_id 還是 123321。

   book.title : RHCSA
   book.author : dywang
   book.book_id : 123456
   book1_id : 123456
   book.title : Python
   book.author : Linda
   book.book_id : 123321
   book2_id : 123321