C# 结构体
在 C# 中,结构体是值类型数据结构。它使得一个单一变量可以存储各种数据类型的相关数据。struct 关键字用于创建结构体。
结构体是用来代表一个记录。假设您想跟踪图书馆中书的动态。您可能想跟踪每本书的以下属性:
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• Title • Author • Subject • Book ID |
一、定义结构体
为了定义一个结构体,您必须使用 struct
语句。struct
语句为程序定义了一个带有多个成员的新的数据类型。
例如,您可以按照如下的方式声明 Book 结构:
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<span class="hljs-keyword">struct</span> Books { <span class="hljs-keyword">public</span> <span class="hljs-keyword">string</span> title; <span class="hljs-keyword">public</span> <span class="hljs-keyword">string</span> author; <span class="hljs-keyword">public</span> <span class="hljs-keyword">string</span> subject; <span class="hljs-keyword">public</span> <span class="hljs-keyword">int</span> book_id; }; |
下面的程序演示了结构的用法:
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<span class="hljs-keyword">using</span> System; <span class="hljs-keyword">struct</span> Books { <span class="hljs-keyword">public</span> <span class="hljs-keyword">string</span> title; <span class="hljs-keyword">public</span> <span class="hljs-keyword">string</span> author; <span class="hljs-keyword">public</span> <span class="hljs-keyword">string</span> subject; <span class="hljs-keyword">public</span> <span class="hljs-keyword">int</span> book_id; }; <span class="hljs-keyword">public</span> <span class="hljs-keyword">class</span> <span class="hljs-title">testStructure</span> { <span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> <span class="hljs-title">Main</span>(<span class="hljs-params"><span class="hljs-keyword">string</span>[] args</span>) </span>{ Books Book1; <span class="hljs-comment">/* 声明 Book1,类型为 Book */</span> Books Book2; <span class="hljs-comment">/* 声明 Book2,类型为 Book */</span> <span class="hljs-comment">/* book 1 详述 */</span> Book1.title = <span class="hljs-string">"C Programming"</span>; Book1.author = <span class="hljs-string">"Nuha Ali"</span>; Book1.subject = <span class="hljs-string">"C Programming Tutorial"</span>; Book1.book_id = <span class="hljs-number">6495407</span>; <span class="hljs-comment">/* book 2 详述 */</span> Book2.title = <span class="hljs-string">"Telecom Billing"</span>; Book2.author = <span class="hljs-string">"Zara Ali"</span>; Book2.subject = <span class="hljs-string">"Telecom Billing Tutorial"</span>; Book2.book_id = <span class="hljs-number">6495700</span>; <span class="hljs-comment">/* 打印 Book1 信息 */</span> Console.WriteLine( <span class="hljs-string">"Book 1 title : {0}"</span>, Book1.title); Console.WriteLine(<span class="hljs-string">"Book 1 author : {0}"</span>, Book1.author); Console.WriteLine(<span class="hljs-string">"Book 1 subject : {0}"</span>, Book1.subject); Console.WriteLine(<span class="hljs-string">"Book 1 book_id :{0}"</span>, Book1.book_id); <span class="hljs-comment">/* 打印 Book2 信息 */</span> Console.WriteLine(<span class="hljs-string">"Book 2 title : {0}"</span>, Book2.title); Console.WriteLine(<span class="hljs-string">"Book 2 author : {0}"</span>, Book2.author); Console.WriteLine(<span class="hljs-string">"Book 2 subject : {0}"</span>, Book2.subject); Console.WriteLine(<span class="hljs-string">"Book 2 book_id : {0}"</span>, Book2.book_id); Console.ReadKey(); } } |
当上面的代码被编译和执行时,它会产生下列结果:
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Book <span class="hljs-number">1</span> title : C Programming Book <span class="hljs-number">1</span> author : Nuha Ali Book <span class="hljs-number">1</span> subject : C Programming Tutorial Book <span class="hljs-number">1</span> book_id : <span class="hljs-number">6495407</span> Book <span class="hljs-number">2</span> title : Telecom Billing Book <span class="hljs-number">2</span> author : Zara Ali Book <span class="hljs-number">2</span> subject : Telecom Billing Tutorial Book <span class="hljs-number">2</span> book_id : <span class="hljs-number">6495700</span> |
二、C# 结构的特点
您已经用了一个简单的名为 Books 的结构。在 C# 中的结构与传统的 C 或 C++ 中的结构不同。C# 中的结构有以下特点:
- 结构可带有方法、字段、索引、属性、运算符方法和事件。
- 结构可定义构造函数,但不能定义析构函数。但是,您不能为结构定义默认的构造函数。默认的构造函数是自动定义的,且不能被改变。
- 与类不同,结构不能继承其他的结构或类。
- 结构不能作为其他结构或类的基础结构。
- 结构可实现一个或多个接口。
- 结构成员不能指定为 abstract、virtual 或 protected。
- 当您使用 New 操作符创建一个结构对象时,会调用适当的构造函数来创建结构。与类不同,结构可以不使用 New 操作符即可被实例化。
- 如果不使用 New 操作符,只有在所有的字段都被初始化之后,字段才被赋值,对象才被使用。
三、类 vs 结构
类和结构有以下几个基本的不同点:
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• 类是引用类型,结构是值类型。 • 结构不支持继承。 • 结构不能声明默认的构造函数。 |
针对上述讨论,让我们重写前面的实例:
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<span class="hljs-keyword">using</span> System; <span class="hljs-keyword">struct</span> Books { <span class="hljs-keyword">private</span> <span class="hljs-keyword">string</span> title; <span class="hljs-keyword">private</span> <span class="hljs-keyword">string</span> author; <span class="hljs-keyword">private</span> <span class="hljs-keyword">string</span> subject; <span class="hljs-keyword">private</span> <span class="hljs-keyword">int</span> book_id; <span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">getValues</span>(<span class="hljs-params"><span class="hljs-keyword">string</span> t, <span class="hljs-keyword">string</span> a, <span class="hljs-keyword">string</span> s, <span class="hljs-keyword">int</span> id</span>) </span>{ title = t; author = a; subject = s; book_id =id; } <span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">display</span>() </span>{ Console.WriteLine(<span class="hljs-string">"Title : {0}"</span>, title); Console.WriteLine(<span class="hljs-string">"Author : {0}"</span>, author); Console.WriteLine(<span class="hljs-string">"Subject : {0}"</span>, subject); Console.WriteLine(<span class="hljs-string">"Book_id :{0}"</span>, book_id); } }; <span class="hljs-keyword">public</span> <span class="hljs-keyword">class</span> <span class="hljs-title">testStructure</span> { <span class="hljs-function"><span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">void</span> <span class="hljs-title">Main</span>(<span class="hljs-params"><span class="hljs-keyword">string</span>[] args</span>) </span>{ Books Book1 = <span class="hljs-keyword">new</span> Books(); <span class="hljs-comment">/* 声明 Book1,类型为 Book */</span> Books Book2 = <span class="hljs-keyword">new</span> Books(); <span class="hljs-comment">/* 声明 Book2,类型为 Book */</span> <span class="hljs-comment">/* book 1 详述 */</span> Book1.getValues(<span class="hljs-string">"C Programming"</span>, <span class="hljs-string">"Nuha Ali"</span>, <span class="hljs-string">"C Programming Tutorial"</span>,<span class="hljs-number">6495407</span>); <span class="hljs-comment">/* book 2 详述 */</span> Book2.getValues(<span class="hljs-string">"Telecom Billing"</span>, <span class="hljs-string">"Zara Ali"</span>, <span class="hljs-string">"Telecom Billing Tutorial"</span>, <span class="hljs-number">6495700</span>); <span class="hljs-comment">/* 打印 Book1 信息 */</span> Book1.display(); <span class="hljs-comment">/* 打印 Book2 信息 */</span> Book2.display(); Console.ReadKey(); } } |
当上面的代码被编译和执行时,它会产生下列结果:
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Title : C Programming Author : Nuha Ali Subject : C Programming Tutorial Book_id : <span class="hljs-number">6495407</span> Title : Telecom Billing Author : Zara Ali Subject : Telecom Billing Tutorial Book_id : <span class="hljs-number">6495700</span> |