LISP结构(Struct)

结构是用户定义的数据类型之一，它允许您组合不同类型的数据项。

• Title
• Author
• Subject
• Book ID

定义结构

LISP中destruct宏允许您定义抽象记录结构，defstruct语句定义了一个新的数据类型，您的程序有多个属性。

要讨论Defstruct宏的格式，让我们编写Book Structure的定义，我们可以将图书结构定义为-

(defstruct book 
   title 
   author 
   subject 
   book-id 
)

• 您可以使用setf更改书籍的组件，例如

(setf (book-book-id book3) 100)

结构示例

创建一个名为main.lisp的新源代码文件，并在其中键入以下代码。

(defstruct book 
   title 
   author 
   subject 
   book-id 
)

( setq book1 (make-book :title "C Programming"
   :author "Nuha Ali" 
   :subject "C-Programming Tutorial"
   :book-id "478")
)

( setq book2 (make-book :title "Telecom Billing"
   :author "Zara Ali" 
   :subject "C-Programming Tutorial"
   :book-id "501")
) 

(write book1)
(terpri)
(write book2)
(setq book3( copy-book book1))
(setf (book-book-id book3) 100) 
(terpri)
(write book3)

当您执行代码时，它返回以下结果-

#S(BOOK :TITLE "C Programming" :AUTHOR "Nuha Ali" :SUBJECT "C-Programming Tutorial" :BOOK-ID "478")
#S(BOOK :TITLE "Telecom Billing" :AUTHOR "Zara Ali" :SUBJECT "C-Programming Tutorial" :BOOK-ID "501")
#S(BOOK :TITLE "C Programming" :AUTHOR "Nuha Ali" :SUBJECT "C-Programming Tutorial" :BOOK-ID 100)