Fortran導出數據類型

Fortran語言可以定義導出的數據類型。導出的數據類型也被稱爲一個結構，它可以包含不同類型的數據對象。

導出的數據類型被用來代表一個記錄。例如要跟蹤在圖書館的書，可能希望跟蹤的每本書有如下屬性：

• 標題- Title
• 作者 - Author
• 科目 - Subject
• 編號 - Book ID

定義一個導出的數據類型

定義一個派生數據類型，類型和端類型的語句被使用。類型語句定義了一個新的數據類型，項目不止一個成員。類型聲明的格式是這樣的：

type type_name
declarations end type

這裏是會聲明書的結構方式：

type Books character(len=50) :: title
character(len=50) :: author
character(len=150) :: subject
integer :: book_id end type Books

訪問結構成員

一個派生數據類型的對象被稱爲結構

類型書籍(Books) 的結構像一個類型聲明語句創建如下：

type(Books) :: book1

結構的組成部分可以使用該組件選擇字符(%)進行訪問 :

book1%title = "C Programming" book1%author = "Nuha Ali" book1%subject = "C Programming Tutorial" book1%book_id = 6495407

請注意，％符號前後沒有空格。

示例

下面的程序說明了上述概念：

program deriveDataType !type declaration
type Books character(len=50) :: title
character(len=50) :: author
character(len=150) :: subject
integer :: book_id end type Books !declaring type variables
type(Books) :: book1
type(Books) :: book2 !accessing the components of the structure

book1%title = "C Programming" book1%author = "Nuha Ali" book1%subject = "C Programming Tutorial" book1%book_id = 6495407 book2%title = "Telecom Billing" book2%author = "Zara Ali" book2%subject = "Telecom Billing Tutorial" book2%book_id = 6495700 !display book info Print *, book1%title Print *, book1%author Print *, book1%subject Print *, book1%book_id Print *, book2%title Print *, book2%author Print *, book2%subject Print *, book2%book_id end program deriveDataType

當上述代碼被編譯和執行時，它產生了以下結果：

C Programming
Nuha Ali
C Programming Tutorial
6495407
Telecom Billing
Zara Ali
Telecom Billing Tutorial
6495700

結構數組

還可以創建一個派生類型的數組：

type(Books), dimension(2) :: list

數組的單個元素，可以訪問如下：

list(1)%title = "C Programming" list(1)%author = "Nuha Ali" list(1)%subject = "C Programming Tutorial" list(1)%book_id = 6495407

下面的程序說明了這個概念：

program deriveDataType !type declaration
type Books character(len=50) :: title
character(len=50) :: author
character(len=150) :: subject
integer :: book_id end type Books !declaring array of books
type(Books), dimension(2) :: list !accessing the components of the structure

list(1)%title = "C Programming" list(1)%author = "Nuha Ali" list(1)%subject = "C Programming Tutorial" list(1)%book_id = 6495407 list(2)%title = "Telecom Billing" list(2)%author = "Zara Ali" list(2)%subject = "Telecom Billing Tutorial" list(2)%book_id = 6495700 !display book info Print *, list(1)%title Print *, list(1)%author Print *, list(1)%subject Print *, list(1)%book_id Print *, list(1)%title Print *, list(2)%author Print *, list(2)%subject Print *, list(2)%book_id end program deriveDataType

當上述代碼被編譯和執行時，它產生了以下結果：

C Programming
Nuha Ali
C Programming Tutorial
6495407
C Programming
Zara Ali
Telecom Billing Tutorial
6495700