【c#】定义类成员（字段、方法、属性）

亦凉 2022-06-12 05:26 228阅读 0赞

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    <div>
      成员定义 
    </div> 
    <div> 
     <br> 
    </div> 
    <ul> 
     <li>public----成员可以由任何代码访问</li> 
     <li>private----成员只能由类中的代码访问（如果没有使用任何关键字，默认使用这个关键字）</li> 
     <li>internal----成员定只能由义他的程序集（命名空间）内部的代码访问</li> 
     <li>protected----成员只能由类或派生类的代码访问</li> 
     <li>protect和internal也可以结合使用 &nbsp; <span style="color:rgb(255,0,0)">protected internal ，</span>表示它们只能由项目中派生类的代码来访问</li> 
     <li>用static关键字修饰，则表示它们是类的静态成员，而不是对象的实例成员</li> 
    </ul> </td> 
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   <td style="border-style:solid; border-width:1px; border-color:rgb(211,211,211); padding:10px; margin:0px; width:100%"> 1.字段的定义</td> 
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    <ul> 
     <li>标准的变量声明格式</li> 
    </ul> 
    <div> 
     <br> 
    </div> 
    <div style="padding:8px; font-family:Monaco,Menlo,Consolas,'Courier New',monospace; color:rgb(51,51,51); background-color:rgb(251,250,248)"> 
     <div>
       class MyClass 
     </div> 
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       { 
     </div> 
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       &nbsp; &nbsp; public int MyInt; 
     </div> 
     <div>
       } 
     </div> 
    </div> 
    <div> 
     <br> 
    </div> 
    <ul> 
     <li>readonly 关键字</li> 
    </ul> 
    <div>
      表示这个字段只能在 
     <span style="color:rgb(255,0,0)">执行构造函数</span>的过程中赋值，或者由 
     <span style="color:rgb(255,0,0)">初始化语句</span>赋值 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      初始化时赋值 
    </div> 
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       class MyClass 
     </div> 
     <div>
       { 
     </div> 
     <div>
       &nbsp; &nbsp; public readonly int MyInt = 2017; 
     </div> 
     <div>
       } 
     </div> 
    </div> 
    <div> 
     <br> 
    </div> 
    <ul> 
     <li>static 关键字，将字段声明为静态</li> 
    </ul> 
    <div> 
     <br> 
    </div> 
    <div style="padding:8px; font-family:Monaco,Menlo,Consolas,'Courier New',monospace; color:rgb(51,51,51); background-color:rgb(251,250,248)"> 
     <div>
       class MyClass 
     </div> 
     <div>
       { 
     </div> 
     <div>
       &nbsp; &nbsp; public static int MyInt; 
     </div> 
     <div>
       } 
     </div> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      注意：静态字段必须通过定义他们的类来访问， 
     <span style="color:rgb(255,0,0)">不能通过实例化的对象来访问</span> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      上面的示例中，只能这样访问 
    </div> 
    <div style="padding:8px; font-family:Monaco,Menlo,Consolas,'Courier New',monospace; color:rgb(51,51,51); background-color:rgb(251,250,248)">
      MyClass.MyInt 
    </div> 
    <div> 
     <br> 
    </div> 
    <ul> 
     <li>const 关键字，可以用 const 关键字定义一个常量，其<span style="color:rgb(255,0,0)">也是静态</span>的，但是不能用 static修饰，否则会出错</li> 
    </ul> </td> 
  </tr> 
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   <td style="border-style:solid; border-width:1px; border-color:rgb(211,211,211); padding:10px; margin:0px; width:100%"> 2.定义方法</td> 
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    <ul> 
     <li>标准函数格式、可访问性和可选的 static 修饰符来声明</li> 
    </ul> 
    <div>
      注意：用static修饰后，只能通过类访问，不能通过实例化的对象访问 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <strong>使用关键字</strong> 
    </div> 
    <ul> 
     <li>virtual----方法可以重写</li> 
     <li>abstract----方法必须在非抽象的派生类中重写（只用于抽象类）</li> 
     <li>override----方法重写了一个基类方法（<span style="color:rgb(255,0,0)">要重写方法，必须用这个关键字</span>）</li> 
     <li>extern----方法定义在其他地方</li> 
    </ul> 
    <div> 
     <br> 
    </div> 
    <div>
      注意： 
    </div> 
    <div>
      如果使用了override，也可以使用 sealed 来指定 派生类中不能对这个方法进一步修改 
    </div> </td> 
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   <td style="border-style:solid; border-width:1px; border-color:rgb(211,211,211); padding:10px; margin:0px; width:100%"> 3.定义属性</td> 
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    <ul> 
     <li>属性是一种类的成员，它的<span style="color:rgb(255,0,0)">实现类似函数</span>，<span style="color:rgb(255,0,0)">访问类似字段</span></li> 
     <li>作用是提供一种<span style="color:rgb(255,0,0)">灵活和安全的机制来访问、修改私有字段</span></li> 
     <li>属性必须依赖于字段</li> 
    </ul> 
    <div> 
     <br> 
    </div> 
    <ul> 
     <li>属性拥有两个类似于函数的块，set 和 get ，set 设置属性的值，get 获取属性的值</li> 
    </ul> 
    <div style="padding:8px; font-family:Monaco,Menlo,Consolas,'Courier New',monospace; color:rgb(51,51,51); background-color:rgb(251,250,248)"> 
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       private int myInt;&nbsp; 
     </div> 
     <div> 
      <br> 
     </div> 
     <div>
       public int MyInt 
     </div> 
     <div>
       {&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; get{ return myInt * 3;}&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; set{ myInt = value / 3;}&nbsp; 
     </div> 
     <div>
       }&nbsp; 
     </div> 
    </div> 
    <div> 
     <br> 
    </div> 
    <ul> 
     <li>这两个块称为 <span style="color:rgb(255,0,0)">访问器</span>，可以用来控制属性的访问级别</li> 
     <li>可以忽略其中的一个块创建只读或只写属性 （没有set的属性是一种<span style="color:rgb(255,0,0)">只读</span>属性，没有get的访问器是一种<span style="color:rgb(255,0,0)">只写</span>属性）</li> 
    </ul> 
    <div>
      注意：这里的只读和只写只适用于外部代码，类中的其他代码依旧能访问其中的数据 
    </div> 
    <ul> 
     <li><span style="color:rgb(255,0,0)">get</span>访问器用来返回字段或者计算 并返回字段，它必须以return或者throw终结</li> 
     <li><span style="color:rgb(255,0,0)">set</span>访问器类似返回类型为void的函数，使用value的隐式参数</li> 
    </ul> 
    <div>
      注意： 
     <span style="color:rgb(255,0,0)">value</span> 关键字表示用户提供的属性值，其类型和属性相同，所以如果属性和字段使用相同的类型，就不用类型转换。 
    </div> 
    <div> 
     <br> 
    </div> 
    <div style="padding:8px; font-family:Monaco,Menlo,Consolas,'Courier New',monospace; color:rgb(51,51,51); background-color:rgb(251,250,248)"> 
     <div>
       //类中MyClass 
     </div> 
     <div>
       private int myInt; 
     </div> 
     <div> 
      <br> 
     </div> 
     <div>
       public int MyInt 
     </div> 
     <div>
       { 
     </div> 
     <div>
       &nbsp; &nbsp; get{ return myInt;} 
     </div> 
     <div>
       &nbsp; &nbsp; set 
     </div> 
     <div>
       &nbsp; &nbsp; { 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; if(value &gt;= 0 &amp;&amp; value &lt;= &nbsp;10)&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; myInt = value; 
     </div> 
     <div>
       &nbsp; &nbsp; } 
     </div> 
     <div>
       } 
     </div> 
     <div> 
      <br> 
     </div> 
     <div>
       //类外使用 
     </div> 
     <div>
       MyClass myObj = new MyClass(); 
     </div> 
     <div> 
      <br> 
     </div> 
     <div>
       for(int i = -1; i &lt; 1; i++) 
     </div> 
     <div>
       { 
     </div> 
     <div>
       &nbsp; &nbsp; myObj.MyInt = i; 
     </div> 
     <div>
       } 
     </div> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      上述代码中，如果赋给属性的值不满足&nbsp;value &gt;= 0 || value &lt;= &nbsp;10，也就是说使用了无效的值，该怎么办？ 
    </div> 
    <ol> 
     <li>什么也不做，如上述代码</li> 
     <li>给字段赋默认值</li> 
     <li>继续执行，就像没发生错误一样，但是记录下该事件，以备将来分析</li> 
     <li>抛出异常</li> 
    </ol> 
    <div>
      一般情况下，后两种处理方式较好，使用 4 的方法，代码如下 
    </div> 
    <div> 
     <br> 
    </div> 
    <div style="padding:8px; font-family:Monaco,Menlo,Consolas,'Courier New',monospace; color:rgb(51,51,51); background-color:rgb(251,250,248)"> 
     <div>
       &nbsp;&nbsp;&nbsp; set 
     </div> 
     <div>
       &nbsp;&nbsp;&nbsp; { 
     </div> 
     <div>
       &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; if (value &gt;= 0 &amp;&amp; value &lt;= 10) 
     </div> 
     <div>
       &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; { 
     </div> 
     <div>
       &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; myInt = value; 
     </div> 
     <div>
       &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; } 
     </div> 
     <div>
       &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; else 
     </div> 
     <div>
       &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; { 
     </div> 
     <div>
       &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; throw (new ArgumentOutOfRangeException("MyIntProp", value, 
     </div> 
     <div>
       &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; "MyIntProp must be assigned a value between 0 and 10")); 
     </div> 
     <div>
       &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; } 
     </div> 
     <div>
       &nbsp;&nbsp;&nbsp; } 
     </div> 
    </div> 
    <div> 
     <br> 
    </div> 
    <ul> 
     <li>属性访问标记可以为public,private,protected,internal,protected internal</li> 
     <li>因为访问器的访问限制必须比属性的访问限制更加严格，所以</li> 
    </ul> 
    <ol> 
     <li style="list-style:none; display:inline"> 
      <ol> 
       <li>不能对接口或者<span style="color:rgb(255,0,0)">显式的接口</span>使用访问修饰符，因为接口里里面所有的默认是public的</li> 
       <li>同时具有get，set访问器时，才允许使用访问修饰符，并且只能有一个使用</li> 
       <li>如果属性有override修饰的时候，访问器修饰符必须与被重写的匹配</li> 
       <li>访问器的可访问级别必须比属性的可访问级别更加严格</li> 
      </ol> </li> 
    </ol> 
    <div> 
     <span style="color:rgb(51,51,51)"><span style="font-family:Monaco,Menlo,Consolas,'Courier New',monospace"><br> </span></span> 
    </div> 
    <div style="padding:8px; font-family:Monaco,Menlo,Consolas,'Courier New',monospace; color:rgb(51,51,51); background-color:rgb(251,250,248)"> 
     <div>
       private int myInt;&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; public int MyInt &nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; {&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; public get { return myInt; }&nbsp; 
      <span style="color:rgb(255,0,0)">//error&nbsp; 因为访问器的级别和属性相同，所以错误（访问器访问级别更加严格）</span> 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; set { myInt = value; }&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; }&nbsp; 
     </div> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      理解： 
    </div> 
    <div>
      首先第四条最容易想到，也是很合理的，毕竟是外围的决定内部的。 
    </div> 
    <div>
      其次，既然第四条可以理解，那么如果 
     <span style="color:rgb(255,0,0)">只有一个访问器</span>的时候，访问器 
     <span style="color:rgb(255,0,0)">访问级别等同属性</span>，如果这个时候再去指 定更加严格的访问级别，那么为何不当初在属性上指定呢？ 
    </div> 
    <div>
      这条理解了，那么为什么必须同时具有get，set才能添加访问修饰符就更加明确了。 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      推理： 
    </div> 
    <div>
      接口中属性是public的，那么如果接口中只有一个get或者set的时候，我们可以在继承中指明另一个访问器的属性。（ 
     <span style="color:rgb(255,0,0)">接口中只有一个访问器，另一个可以在继承中指明访问级别</span>） 
    </div> 
    <div>
      但是如果接口中同时具有get，set，那么按照派生和继承的匹配性，这时候就不能这样再指定访问器的访问限制了。 （ 
     <span style="color:rgb(255,0,0)">接口中有两个访问器，不能再指定访问器的访问级别</span>） 
    </div> 
    <div> 
     <span style="color:rgb(51,51,51)"><span style="font-family:Monaco,Menlo,Consolas,'Courier New',monospace"><br> </span></span> 
    </div> 
    <div style="padding:8px; font-family:Monaco,Menlo,Consolas,'Courier New',monospace; color:rgb(51,51,51); background-color:rgb(251,250,248)"> 
     <div>
       public interface ISomeInterface&nbsp; 
     </div> 
     <div>
       {&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; int TestProperty&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; {&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; // No access modifier allowed here&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; // because this is an interface.&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; get;&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; }&nbsp; 
     </div> 
     <div>
       }&nbsp; 
     </div> 
     <div> 
      <br> 
     </div> 
     <div> 
      <br> 
     </div> 
     <div>
       public class TestClass : ISomeInterface&nbsp; 
     </div> 
     <div>
       {&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; public int TestProperty&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; {&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; // Cannot use access modifier here because&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; // this is an interface implementation.&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; get { return 10; }&nbsp; 
     </div> 
     <div> 
      <br> 
     </div> 
     <div> 
      <br> 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; // Interface property does not have set accessor,&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; // so access modifier is allowed.&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; protected set { }&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; }&nbsp; 
     </div> 
     <div>
       }&nbsp; 
     </div> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <ul> 
     <li><span style="color:rgb(51,51,51)"><span style="font-family:Monaco,Menlo,Consolas,'Courier New',monospace">可以用static 修饰属性，以便随时访问</span></span></li> 
    </ul> 
    <div style="padding:8px; font-family:Monaco,Menlo,Consolas,'Courier New',monospace; color:rgb(51,51,51); background-color:rgb(251,250,248)"> 
     <div>
       private static int counter;&nbsp; 
     </div> 
     <div>
       public static int Counter&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; {&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; get { return counter; }&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; }&nbsp; 
     </div> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <ul> 
     <li>属性隐藏</li> 
    </ul> 
    <div> 
     <br> 
    </div> 
    <div style="padding:8px; font-family:Monaco,Menlo,Consolas,'Courier New',monospace; color:rgb(51,51,51); background-color:rgb(251,250,248)"> 
     <div>
       public class Employee&nbsp; 
     </div> 
     <div>
       {&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; private string name;&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; public string Name&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; {&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; get { return name; }&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; set { name = value; }&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; }&nbsp; 
     </div> 
     <div>
       }&nbsp; 
     </div> 
     <div> 
      <br> 
     </div> 
     <div>
       public class Manager : Employee&nbsp; 
     </div> 
     <div>
       {&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; private string name;&nbsp; 
     </div> 
     <div> 
      <br> 
     </div> 
     <div> 
      <br> 
     </div> 
     <div>
       &nbsp; &nbsp; // Notice the use of the new modifier:&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; public new string Name // use new to hide property in base class&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; {&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; get { return name; }&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; set { name = value + ", Manager"; }&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; }&nbsp; 
     </div> 
     <div>
       }&nbsp; 
     </div> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <ul> 
     <li>virtual来修饰属性，派生类使用override来重写属性</li> 
    </ul> 
    <div> 
     <br> 
    </div> 
    <div style="padding:8px; font-family:Monaco,Menlo,Consolas,'Courier New',monospace; color:rgb(51,51,51); background-color:rgb(251,250,248)"> 
     <div>
       public class Parent&nbsp; 
     </div> 
     <div>
       {&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; public virtual int TestProperty&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; {&nbsp; 
     </div> 
     <div> 
      <br> 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; protected set { }&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; get { return 0; }&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; }&nbsp; 
     </div> 
     <div>
       }&nbsp; 
     </div> 
     <div>
       public class Kid : Parent&nbsp; 
     </div> 
     <div>
       {&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; public override int TestProperty&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; {&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; protected set { }&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; get { return 0; }&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; }&nbsp; 
     </div> 
     <div>
       }&nbsp; 
     </div> 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <ul> 
     <li>abstract 修饰属性，派生类来实现属性</li> 
    </ul> 
    <div> 
     <br> 
    </div> 
    <div style="padding:8px; font-family:Monaco,Menlo,Consolas,'Courier New',monospace; color:rgb(51,51,51); background-color:rgb(251,250,248)"> 
     <div>
       abstract class Shape&nbsp; 
     </div> 
     <div>
       {&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; public abstract double Area&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; {&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; get;&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; set;&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; }&nbsp; 
     </div> 
     <div>
       } 
     </div> 
     <div> 
      <br> 
     </div> 
     <div>
       class Square : Shape&nbsp; 
     </div> 
     <div>
       {&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; public double side;&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; public override double Area&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; {&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; get&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return side * side;&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; set&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; {&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; side = System.Math.Sqrt(value);&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; 
     </div> 
     <div>
       &nbsp; &nbsp; }&nbsp; 
     </div> 
     <div>
       }&nbsp; &nbsp; 
     </div> 
    </div> 
    <div> 
     <br> 
    </div> 
    <ul> 
     <li>sealed 修饰属性，派生类不能修改属性</li> 
    </ul> 
    <div> 
     <br> 
    </div> 
    <ul> 
     <li>接口属性</li> 
    </ul> 
    <div>
      接口属性不具有函数体 
    </div> 
    <div> 
     <br> 
    </div> 
    <div> 
     <br> 
    </div> 
    <ul> 
     <li>自动属性</li> 
    </ul> 
    <div>
      当属性访问器中不需要其他访问逻辑时候，就可以使用自动属性，使代码更加简洁 
    </div> 
    <div> 
     <br> 
    </div> 
    <div style="padding:8px; font-family:Monaco,Menlo,Consolas,'Courier New',monospace; color:rgb(51,51,51); background-color:rgb(251,250,248)">
      public double TotalPurchases { get; set; }&nbsp; 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      有两个使用场景： 
    </div> 
    <div> 
     <br> 
    </div> 
    <div>
      在接口中定义，继承接口的类就可以用了。 
    </div> 
    <div>
      当有个字段不需要限制访问，为了编程习惯又不想写成公有字段，同时有懒得主动写那个字段名的时候，就使用自动属性吧。 
    </div> </td> 
  </tr> 
 </tbody> 
</table>