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Type.HasElementTypeImpl 方法

  • 项目

当在派生类中重写时，实现 HasElementType 属性 (Property)，确定当前 Type 是否包含另一类型或对其引用；即，当前 Type 是否是数组、指针或由引用传递。

**命名空间:**System
**程序集:**mscorlib（在 mscorlib.dll 中）

语法

声明
Protected MustOverride Function HasElementTypeImpl As Boolean
用法
Dim returnValue As Boolean

returnValue = Me.HasElementTypeImpl

protected abstract bool HasElementTypeImpl ()

protected:
virtual bool HasElementTypeImpl () abstract

protected abstract boolean HasElementTypeImpl ()

protected abstract function HasElementTypeImpl () : boolean

返回值

如果 Type 为数组、指针或按引用传递，则为 true；否则为 false。

备注

例如，Type.GetType("Int32[]").HasElementTypeImpl 返回 true，而 Type.GetType("Int32").HasElementTypeImpl 返回 false。对于“Int32*”和“Int32&”，HasElementTypeImpl 也返回 true。

示例

下面的示例定义类 MyTypeDelegator，该类会重写 HasElementTypeImpl 方法。主类将检查 HasElementType 属性 (Property) 并显示元素类型。

Imports System
Imports System.Reflection
Imports Microsoft.VisualBasic
Public Class MyTypeDelegator
    Inherits TypeDelegator
    Public myElementType As String = Nothing
    Private myType As Type = Nothing
    Public Sub New(ByVal myType As Type)
        MyBase.New(myType)
        Me.myType = myType
    End Sub 'New
    ' Override Type.HasElementTypeImpl().
    Protected Overrides Function HasElementTypeImpl() As Boolean
        ' Determine whether the type is an array.
        If myType.IsArray Then
            myElementType = "array"
            Return True
        End If
        ' Determine whether the type is a reference.
        If myType.IsByRef Then
            myElementType = "reference"
            Return True
        End If
        ' Determine whether the type is a pointer.
        If myType.IsPointer Then
            myElementType = "pointer"
            Return True
        End If
        ' The type is not a reference, array, or pointer type.
        Return False
    End Function 'HasElementTypeImpl
End Class 'MyTypeDelegator
Public Class Type_HasElementTypeImpl
    Public Shared Sub Main()
        Try
            Dim myInt As Integer = 0
            Dim myArray(4) As Integer
            Dim myType As New MyTypeDelegator(myArray.GetType())
            Console.WriteLine(ControlChars.NewLine + "Determine whether a variable refers to an array or pointer or reference type." + ControlChars.NewLine)
            ' Determine whether myType is an array, pointer, reference type.  
            If myType.HasElementType Then
                Console.WriteLine("The type of myArray is {0}.", myType.myElementType.ToString())
            Else
                Console.WriteLine("myArray is not an array, pointer, or reference type.")
            End If
            myType = New MyTypeDelegator(myInt.GetType())
            ' Determine whether myType is an array, pointer, reference type. 
            If myType.HasElementType Then
                Console.WriteLine("The type of myInt is {0}.", myType.myElementType.ToString())
            Else
                Console.WriteLine("myInt is not an array, pointer, or reference type.")
            End If
        Catch e As Exception
            Console.WriteLine("Exception: {0}", e.Message.ToString())
        End Try
    End Sub 'Main
End Class 'Type_HasElementTypeImpl

using System;
using System.Reflection;
public class MyTypeDelegator : TypeDelegator
{
    public string myElementType = null;
    private Type myType = null ; 
    public MyTypeDelegator(Type myType) : base(myType)
    {
        this.myType = myType;
    }
    // Override Type.HasElementTypeImpl().
    protected override bool HasElementTypeImpl()
    {
        // Determine whether the type is an array.
        if(myType.IsArray)
        {
            myElementType = "array";
            return true;
        }
        // Determine whether the type is a reference.
        if(myType.IsByRef)
        {
            myElementType = "reference";
            return true;
        }
        // Determine whether the type is a pointer.
        if(myType.IsPointer)
        { 
            myElementType = "pointer";
            return true;
        }
        // Return false if the type is not a reference, array, or pointer type.
        return false;
    }  
}
public class Type_HasElementTypeImpl
{
    public static void Main()
    {
        try
        {
            int myInt = 0 ; 
            int[] myArray = new int[5];
            MyTypeDelegator myType = new MyTypeDelegator(myArray.GetType());
            // Determine whether myType is an array, pointer, reference type.  
            Console.WriteLine("\nDetermine whether a variable is an array, pointer, or reference type.\n");
            if( myType.HasElementType)
                Console.WriteLine("The type of myArray is {0}.", myType.myElementType);
            else
                Console.WriteLine("myArray is not an array, pointer, or reference type.");
            myType = new MyTypeDelegator(myInt.GetType());
            // Determine whether myType is an array, pointer, reference type. 
            if( myType.HasElementType)
                Console.WriteLine("The type of myInt is {0}.", myType.myElementType);
            else
                Console.WriteLine("myInt is not an array, pointer, or reference type.");
        }
        catch( Exception e )
        {
            Console.WriteLine("Exception: {0}", e.Message);
        }
    }
}

using namespace System;
using namespace System::Reflection;
public ref class MyTypeDelegator: public TypeDelegator
{
public:
   String^ myElementType;

private:
   Type^ myType;

public:
   MyTypeDelegator( Type^ myType )
      : TypeDelegator( myType )
   {
      this->myType = myType;
   }


protected:

   // Override Type::HasElementTypeImpl().
   virtual bool HasElementTypeImpl() override
   {
      
      // Determine whether the type is an array.
      if ( myType->IsArray )
      {
         myElementType = "array";
         return true;
      }

      
      // Determine whether the type is a reference.
      if ( myType->IsByRef )
      {
         myElementType = "reference";
         return true;
      }

      
      // Determine whether the type is a pointer.
      if ( myType->IsPointer )
      {
         myElementType = "pointer";
         return true;
      }

      
      // Return false if the type is not a reference, array, or pointer type.
      return false;
   }

};

int main()
{
   try
   {
      int myInt = 0;
      array<Int32>^myArray = gcnew array<Int32>(5);
      MyTypeDelegator^ myType = gcnew MyTypeDelegator( myArray->GetType() );
      
      // Determine whether myType is an array, pointer, reference type.
      Console::WriteLine( "\nDetermine whether a variable is an array, pointer, or reference type.\n" );
      if ( myType->HasElementType )
            Console::WriteLine( "The type of myArray is {0}.", myType->myElementType );
      else
            Console::WriteLine( "myArray is not an array, pointer, or reference type." );
      myType = gcnew MyTypeDelegator( myInt.GetType() );
      
      // Determine whether myType is an array, pointer, reference type.
      if ( myType->HasElementType )
            Console::WriteLine( "The type of myInt is {0}.", myType->myElementType );
      else
            Console::WriteLine( "myInt is not an array, pointer, or reference type." );
   }
   catch ( Exception^ e ) 
   {
      Console::WriteLine( "Exception: {0}", e->Message );
   }

}

import System.*;
import System.Reflection.*;

public class MyTypeDelegator extends TypeDelegator
{
    public String myElementType = null;
    private Type myType = null;

    public MyTypeDelegator(Type myType)
    {
        super(myType);
        this.myType = myType;
    } //MyTypeDelegator

    // Override Type.HasElementTypeImpl().
    protected boolean HasElementTypeImpl()
    {
        // Determine whether the type is an array.
        if (myType.get_IsArray()) {
            myElementType = "array";
            return true;
        }
        // Determine whether the type is a reference.
        if (myType.get_IsByRef()) {
            myElementType = "reference";
            return true;
        }
        // Determine whether the type is a pointer.
        if (myType.get_IsPointer()) {
            myElementType = "pointer";
            return true;
        }
        // Return false if the type is not a reference, array, or pointer type.
        return false;
    } //HasElementTypeImpl
} //MyTypeDelegator

public class Type_HasElementTypeImpl
{
    public static void main(String[] args)
    {
        try {
            int myInt = 0;
            int myArray[] = new int[5];
            MyTypeDelegator myType = new MyTypeDelegator(myArray.GetType());
            // Determine whether myType is an array, pointer, reference type.  
            Console.WriteLine("\nDetermine whether a variable is an array, pointer," 
                + " or reference type.\n");
            if (myType.get_HasElementType()) {
                Console.WriteLine("The type of myArray is {0}.", myType.
                    myElementType);
            }
            else {
                Console.WriteLine("myArray is not an array, pointer,"
                    + "or reference type.");
            }
            myType = new MyTypeDelegator(((System.Int32)myInt).GetType()); 
            // Determine whether myType is an array, pointer, reference type. 
            if (myType.get_HasElementType()) {
                Console.WriteLine("The type of myInt is {0}.", myType.
                    myElementType);
            }
            else {
                Console.WriteLine("myInt is not an array, pointer," 
                    + " or reference type.");
            }
        }
        catch (System.Exception e) {
            Console.WriteLine("Exception: {0}", e.get_Message());
        }
    } //main
} //Type_HasElementTypeImpl

平台

Windows 98、Windows 2000 SP4、Windows CE、Windows Millennium Edition、Windows Mobile for Pocket PC、Windows Mobile for Smartphone、Windows Server 2003、Windows XP Media Center Edition、Windows XP Professional x64 Edition、Windows XP SP2、Windows XP Starter Edition

.NET Framework 并不是对每个平台的所有版本都提供支持。有关受支持版本的列表，请参见系统要求。

版本信息

.NET Framework

受以下版本支持：2.0、1.1、1.0

.NET Compact Framework

受以下版本支持：2.0、1.0

请参见

参考

Type 类
Type 成员
System 命名空间
HasElementType
IsArray
IsPointer
IsByRef
GetElementType
GetType