D語言結(jié)構(gòu)體

D語言數(shù)組允許定義類型的變量，可容納同類但是結(jié)構(gòu)體幾個數(shù)據(jù)項，它允許結(jié)合不同類型的數(shù)據(jù)項提供另一種用戶定義的數(shù)據(jù)類型。

結(jié)構(gòu)用來表示一個記錄，假設(shè)要跟蹤圖書館中的書籍?？赡芟Ｍ櫫私饷勘緯囊韵聦傩裕?/p>

• 書名

• 作者

• 科目

• 書籍編號ID

定義一個結(jié)構(gòu)體

要定義一個結(jié)構(gòu)，必須使用結(jié)構(gòu)體struct語句。該結(jié)構(gòu)語句定義了一個新的數(shù)據(jù)類型，項目不止一個成員。該結(jié)構(gòu)語句的格式是這樣的：

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

結(jié)構(gòu)體標(biāo)簽是可選的，每個成員的定義是正常的變量定義，比如int i; or float f; 或任何其他有效的變量定義。在該結(jié)構(gòu)的定義的結(jié)尾，最后的分號之前，可以指定一個或多個結(jié)構(gòu)變量，但它是可選的。這里是將聲明書的結(jié)構(gòu)體：

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

訪問結(jié)構(gòu)成員

要訪問一個結(jié)構(gòu)的任何成員，我們使用成員訪問運(yùn)算符(.)成員訪問運(yùn)算編碼為結(jié)構(gòu)體變量名，而我們希望訪問結(jié)構(gòu)成員之間的時間段。可以使用struct關(guān)鍵字來定義結(jié)構(gòu)類型的變量。下面是例子來說明結(jié)構(gòu)的用法：

import std.stdio;

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

void main( )
{
   Books Book1;        /* Declare Book1 of type Book */
   Books Book2;        /* Declare Book2 of type Book */

   /* book 1 specification */
   Book1.title = "D Programming".dup;
   Book1.author = "Raj".dup;
   Book1.subject = "D Programming Tutorial".dup;
   Book1.book_id = 6495407;

   /* book 2 specification */
   Book2.title = "Lua Programming".dup;
   Book2.author = "Raj".dup;
   Book2.subject = "Lua Programming Tutorial".dup;
   Book2.book_id = 6495700;

   /* print Book1 info */
   writeln( "Book 1 title : ", Book1.title);
   writeln( "Book 1 author : ", Book1.author);
   writeln( "Book 1 subject : ", Book1.subject);
   writeln( "Book 1 book_id : ", Book1.book_id);

   /* print Book2 info */
   writeln( "Book 2 title : ", Book2.title);
   writeln( "Book 2 author : ", Book2.author);
   writeln( "Book 2 subject : ", Book2.subject);
   writeln( "Book 2 book_id : ", Book2.book_id);
}

當(dāng)上面的代碼被編譯并執(zhí)行，它會產(chǎn)生以下結(jié)果：

Book 1 title : D Programming
Book 1 author : Raj
Book 1 subject : D Programming Tutorial
Book 1 book_id : 6495407
Book 2 title : Lua Programming
Book 2 author : Raj
Book 2 subject : Lua Programming Tutorial
Book 2 book_id : 6495700

結(jié)構(gòu)作為函數(shù)的參數(shù)

可以傳遞一個結(jié)構(gòu)非常類似的方式函數(shù)作為參數(shù)傳遞任何其他變量或指針。訪問在上面的例子已經(jīng)使用類似的方式的結(jié)構(gòu)變量：

import std.stdio;

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

void main( )
{
   Books Book1;        /* Declare Book1 of type Book */
   Books Book2;        /* Declare Book2 of type Book */

   /* book 1 specification */
   Book1.title = "D Programming".dup;
   Book1.author = "Raj".dup;
   Book1.subject = "D Programming Tutorial".dup;
   Book1.book_id = 6495407;

   /* book 2 specification */
   Book2.title = "Lua Programming".dup;
   Book2.author = 
            
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