C# typeof()实例详解

浅浅的花香味﹌ 2022-02-24 09:12 245阅读 0赞

用于获取类型的 **System.Type** 对象。**typeof** 表达式采用以下形式：

System.Type type = typeof(int);

![clear.gif][] 备注

若要获取表达式的运行时类型，可以使用 .NET Framework 方法 GetType，如下所示：

int i = 0;
    System.Type type = i.GetType();

**typeof** 运算符也能用于公开的泛型类型。具有不止一个类型参数的类型的规范中必须有适当数量的逗号。不能重载  **typeof** 运算符。

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      <code>示例&nbsp; </code> 
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      <code>// cs_operator_typeof.cs </code> 
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      <code>using</code> 
      <code> System; </code> 
     </div> 
     <div> 
      <code>using</code> 
      <code> System.Reflection; </code> 
     </div> 
     <div> 
      <code>public</code> 
      <code> class</code> 
      <code>SampleClass </code> 
     </div> 
     <div> 
      <code>{ </code> 
     </div> 
     <div> 
      <code>public</code> 
      <code> int</code> 
      <code>sampleMember; </code> 
     </div> 
     <div> 
      <code>public</code> 
      <code> void</code> 
      <code>SampleMethod() {} </code> 
     </div> 
     <div> 
      <code>static</code> 
      <code> void</code> 
      <code>Main() </code> 
     </div> 
     <div> 
      <code>{ </code> 
     </div> 
     <div> 
      <code>Type t = </code> 
      <code>typeof</code> 
      <code>(SampleClass); </code> 
     </div> 
     <div> 
      <code>// Alternatively, you could use </code> 
     </div> 
     <div> 
      <code>// SampleClass obj = new SampleClass(); </code> 
     </div> 
     <div> 
      <code>// Type t = obj.GetType(); </code> 
     </div> 
     <div> 
      <code>Console.WriteLine(</code> 
      <code>"Methods:"</code> 
      <code>); </code> 
     </div> 
     <div> 
      <code>MethodInfo[] methodInfo = t.GetMethods(); </code> 
     </div> 
     <div> 
      <code>foreach</code> 
      <code>(MethodInfo mInfo </code> 
      <code>in</code> 
      <code>methodInfo) </code> 
     </div> 
     <div> 
      <code>Console.WriteLine(mInfo.ToString()); </code> 
     </div> 
     <div> 
      <code>Console.WriteLine(</code> 
      <code>"Members:"</code> 
      <code>); </code> 
     </div> 
     <div> 
      <code>MemberInfo[] memberInfo = t.GetMembers(); </code> 
     </div> 
     <div> 
      <code>foreach</code> 
      <code>(MemberInfo mInfo </code> 
      <code>in</code> 
      <code>memberInfo) </code> 
     </div> 
     <div> 
      <code>Console.WriteLine(mInfo.ToString()); </code> 
     </div> 
     <div> 
      <code>} </code> 
     </div> 
     <div> 
      <code>} </code> 
     </div> 
     <div> 
      <code>输出 </code> 
     </div> 
     <div> 
      <code>Methods: </code> 
     </div> 
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      <code>Void SampleMethod() </code> 
     </div> 
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      <code>System.Type GetType() </code> 
     </div> 
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      <code>System.String ToString() </code> 
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      <code>Boolean Equals(System.Object) </code> 
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      <code>Int32 GetHashCode() </code> 
     </div> 
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      <code>Members: </code> 
     </div> 
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      <code>Void SampleMethod() </code> 
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      <code>System.Type GetType() </code> 
     </div> 
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      <code>System.String ToString() </code> 
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      <code>Boolean Equals(System.Object) </code> 
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      <code>Int32 GetHashCode() </code> 
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      <code>Void .ctor() </code> 
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      <code>Int32 sampleMember </code> 
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      <code>此示例使用 GetType 方法确定用来包含数值计算的结果的类型。这取决于结果数字的存储要求。 </code> 
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      <code>&nbsp;</code>&nbsp; 
     </div> 
     <div> 
      <code>// cs_operator_typeof2.cs </code> 
     </div> 
     <div> 
      <code>using</code> 
      <code>System; </code> 
     </div> 
     <div> 
      <code>class</code> 
      <code>GetTypeTest </code> 
     </div> 
     <div> 
      <code>{ </code> 
     </div> 
     <div> 
      <code>static</code> 
      <code>void</code> 
      <code>Main() </code> 
     </div> 
     <div> 
      <code>{ </code> 
     </div> 
     <div> 
      <code>int</code> 
      <code> radius = 3; </code> 
     </div> 
     <div> 
      <code>Console.WriteLine(</code> 
      <code>"Area = {0}"</code> 
      <code>, radius * radius * Math.PI); </code> 
     </div> 
     <div> 
      <code>Console.WriteLine(</code> 
      <code>"The type is {0}"</code> 
      <code>, </code> 
     </div> 
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      <code>(radius * radius * Math.PI).GetType() </code> 
     </div> 
     <div> 
      <code>); </code> 
     </div> 
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      <code>} </code> 
     </div> 
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      <code>} </code> 
     </div> 
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      <code>输出 </code> 
     </div> 
     <div> 
      <code>Area = 28.2743338823081 </code> 
     </div> 
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      <code>The type </code> 
      <code>is</code> 
      <code>System.Double</code> 
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[http://www.cnblogs.com/lm3515/archive/2010/09/02/1815725.html][http_www.cnblogs.com_lm3515_archive_2010_09_02_1815725.html]

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[Link 1]: http://www.cnblogs.com/lm3515/archive/2010/09/02/1815725.html#
[http_www.cnblogs.com_lm3515_archive_2010_09_02_1815725.html]: http://www.cnblogs.com/lm3515/archive/2010/09/02/1815725.html