Object.GetType 方法

定義

取得目前執行個體的 TypeGets the Type of the current instance.

public:
 Type ^ GetType();
public Type GetType ();
member this.GetType : unit -> Type
Public Function GetType () As Type

傳回

目前執行個體的確切執行階段類型。The exact runtime type of the current instance.

範例

下列程式碼範例會示範 GetType 傳回目前實例的執行時間類型。The following code example demonstrates that GetType returns the runtime type of the current instance.

using namespace System;

public ref class MyBaseClass {};

public ref class MyDerivedClass: MyBaseClass{};

int main()
{
   MyBaseClass^ myBase = gcnew MyBaseClass;
   MyDerivedClass^ myDerived = gcnew MyDerivedClass;
   Object^ o = myDerived;
   MyBaseClass^ b = myDerived;
   Console::WriteLine( "mybase: Type is {0}", myBase->GetType() );
   Console::WriteLine( "myDerived: Type is {0}", myDerived->GetType() );
   Console::WriteLine( "object o = myDerived: Type is {0}", o->GetType() );
   Console::WriteLine( "MyBaseClass b = myDerived: Type is {0}", b->GetType() );
}

/*

This code produces the following output.

mybase: Type is MyBaseClass
myDerived: Type is MyDerivedClass
object o = myDerived: Type is MyDerivedClass
MyBaseClass b = myDerived: Type is MyDerivedClass 

*/
using System;

public class MyBaseClass {
}

public class MyDerivedClass: MyBaseClass {
}

public class Test 
{
   public static void Main() 
   {
      MyBaseClass myBase = new MyBaseClass();
      MyDerivedClass myDerived = new MyDerivedClass();
      object o = myDerived;
      MyBaseClass b = myDerived;

      Console.WriteLine("mybase: Type is {0}", myBase.GetType());
      Console.WriteLine("myDerived: Type is {0}", myDerived.GetType());
      Console.WriteLine("object o = myDerived: Type is {0}", o.GetType());
      Console.WriteLine("MyBaseClass b = myDerived: Type is {0}", b.GetType());
   }
}
// The example displays the following output:
//    mybase: Type is MyBaseClass
//    myDerived: Type is MyDerivedClass
//    object o = myDerived: Type is MyDerivedClass
//    MyBaseClass b = myDerived: Type is MyDerivedClass 
' Define a base and a derived class.
Public Class MyBaseClass
End Class 

Public Class MyDerivedClass : Inherits MyBaseClass
End Class 

Public Class Test
    Public Shared Sub Main() 
        Dim base As New MyBaseClass()
        Dim derived As New MyDerivedClass()
        Dim o As Object = derived
        Dim b As MyBaseClass = derived
        
        Console.WriteLine("base.GetType returns {0}", base.GetType())
        Console.WriteLine("derived.GetType returns {0}", derived.GetType())
        Console.WriteLine("Dim o As Object = derived; o.GetType returns {0}", o.GetType())
        Console.WriteLine("Dim b As MyBaseClass = derived; b.Type returns {0}", b.GetType())
    End Sub 
End Class 
' The example displays the following output:
'    base.GetType returns MyBaseClass
'    derived.GetType returns MyDerivedClass
'    Dim o As Object = derived; o.GetType returns MyDerivedClass
'    Dim b As MyBaseClass = derived; b.Type returns MyDerivedClass

備註

因為 System.Object 是 .NET 類型系統中所有類型的基類,所以可以使用 GetType 方法來傳回代表所有 .NET 類型的 Type 物件。Because System.Object is the base class for all types in the .NET type system, the GetType method can be used to return Type objects that represent all .NET types. .NET 會辨識下列五種類型的類別:.NET recognizes the following five categories of types:

對於具有相同執行時間類型 xy 的兩個物件,Object.ReferenceEquals(x.GetType(),y.GetType()) 會傳回 trueFor two objects x and y that have identical runtime types, Object.ReferenceEquals(x.GetType(),y.GetType()) returns true. 下列範例會搭配使用 GetType 方法與 ReferenceEquals 方法,以判斷某個數值是否與其他兩個數值具有相同的類型。The following example uses the GetType method with the ReferenceEquals method to determine whether one numeric value is the same type as two other numeric values.

int n1 = 12;
int n2 = 82;
long n3 = 12;

Console.WriteLine("n1 and n2 are the same type: {0}",
                  Object.ReferenceEquals(n1.GetType(), n2.GetType()));
Console.WriteLine("n1 and n3 are the same type: {0}",
                  Object.ReferenceEquals(n1.GetType(), n3.GetType()));

// The example displays the following output:
//       n1 and n2 are the same type: True
//       n1 and n3 are the same type: False      
Module Example
   Public Sub Main()
      Dim n1 As Integer = 12
      Dim n2 As Integer = 82
      Dim n3 As Long = 12
      
      Console.WriteLine("n1 and n2 are the same type: {0}",
                        Object.ReferenceEquals(n1.GetType(), n2.GetType()))
      Console.WriteLine("n1 and n3 are the same type: {0}",
                        Object.ReferenceEquals(n1.GetType(), n3.GetType()))
   End Sub
End Module
' The example displays the following output:
'       n1 and n2 are the same type: True
'       n1 and n3 are the same type: False      

注意

若要判斷物件是否為特定類型,您可以使用語言的類型比較關鍵字或結構。To determine whether an object is a specific type, you can use your language's type comparison keyword or construct. 例如,您可以使用 Visual Basic 中的 TypeOf…Is 結構,或中C#的 is 關鍵字。For example, you can use the TypeOf…Is construct in Visual Basic or the is keyword in C#.

衍生自 Object的所有類型都會繼承 GetType 方法。The GetType method is inherited by all types that derive from Object. 這表示除了使用您自己的語言的比較關鍵字之外,您還可以使用 GetType 方法來判斷特定物件的類型,如下列範例所示。This means that, in addition to using your own language's comparison keyword, you can use the GetType method to determine the type of a particular object, as the following example shows.

object[] values = { (int) 12, (long) 10653, (byte) 12, (sbyte) -5,
                   16.3, "string" }; 
foreach (var value in values) {
   Type t = value.GetType();
   if (t.Equals(typeof(byte)))
      Console.WriteLine("{0} is an unsigned byte.", value);
   else if (t.Equals(typeof(sbyte)))
      Console.WriteLine("{0} is a signed byte.", value);
   else if (t.Equals(typeof(int)))   
      Console.WriteLine("{0} is a 32-bit integer.", value);
   else if (t.Equals(typeof(long)))   
      Console.WriteLine("{0} is a 32-bit integer.", value);
   else if (t.Equals(typeof(double)))
      Console.WriteLine("{0} is a double-precision floating point.", 
                        value);
   else
      Console.WriteLine("'{0}' is another data type.", value);
}

// The example displays the following output:
//    12 is a 32-bit integer.
//    10653 is a 32-bit integer.
//    12 is an unsigned byte.
//    -5 is a signed byte.
//    16.3 is a double-precision floating point.
//    'string' is another data type.
Module Example
   Public Sub Main()
      Dim values() As Object = { 12, CLng(10653), CByte(12), 
                                 CSbyte(-5), 16.3, "string" } 
      For Each value In values
         Dim t AS Type = value.GetType()
         If t.Equals(GetType(Byte))
            Console.WriteLine("{0} is an unsigned byte.", value)
         ElseIf t.Equals(GetType(SByte))
            Console.WriteLine("{0} is a signed byte.", value)
         ElseIf t.Equals(GetType(Integer))   
            Console.WriteLine("{0} is a 32-bit integer.", value)
         ElseIf t.Equals(GetType(Long))   
            Console.WriteLine("{0} is a 32-bit integer.", value)
         ElseIf t.Equals(GetType(Double))
            Console.WriteLine("{0} is a double-precision floating point.", 
                              value)
         Else
            Console.WriteLine("'{0}' is another data type.", value)
         End If   
      Next      
   End Sub
End Module
' The example displays the following output:
'       12 is a 32-bit integer.
'       10653 is a 32-bit integer.
'       12 is an unsigned byte.
'       -5 is a signed byte.
'       16.3 is a double-precision floating point.
'       'string' is another data type.

Type 物件會公開與目前 Object的類別相關聯的中繼資料。The Type object exposes the metadata associated with the class of the current Object.

適用於

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