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Type.HasElementTypeImpl Method

When overridden in a derived class, implements the HasElementType property and determines whether the current Type encompasses or refers to another type; that is, whether the current Type is an array, a pointer, or is passed by reference.

[Visual Basic]
Protected MustOverride Function HasElementTypeImpl() As Boolean
[C#]
protected abstract bool HasElementTypeImpl();
[C++]
protected: virtual bool HasElementTypeImpl() = 0;
[JScript]
protected abstract function HasElementTypeImpl() : Boolean;

Return Value

true if the Type is an array, a pointer, or is passed by reference; otherwise, false.

Remarks

For example, Type.GetType("Int32[]").HasElementTypeImpl returns true, but Type.GetType("Int32").HasElementTypeImpl returns false. HasElementTypeImpl also returns true for "Int32*" and "Int32&".

Example

[Visual Basic, C#, C++] The following example defines the class MyTypeDelegator, which overrides the HasElementTypeImpl method. The main class checks for the HasElementType property and displays the element type.

[Visual Basic] 
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

[C#] 
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);
        }
    }
}

[C++] 
#using <mscorlib.dll>

using namespace System;
using namespace System::Reflection;
public __gc class MyTypeDelegator : public TypeDelegator {
public:
   String* myElementType;
private:
   Type* myType;
public:
   MyTypeDelegator(Type* myType) : TypeDelegator(myType) {
      this->myType = myType;
   }
   // Override Type::HasElementTypeImpl().
protected:
   bool HasElementTypeImpl() {
      // Determine whether the type is an array.
      if (myType->IsArray) {
         myElementType = S"array";
         return true;
      }
      // Determine whether the type is a reference.
      if (myType->IsByRef) {
         myElementType = S"reference";
         return true;
      }
      // Determine whether the type is a pointer.
      if (myType->IsPointer) {
         myElementType = S"pointer";
         return true;
      }
      // Return false if the type is not a reference, array, or pointer type.
      return false;
   }
};

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

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework, Common Language Infrastructure (CLI) Standard

See Also

Type Class | Type Members | System Namespace | HasElementType | IsArray | IsPointer | IsByRef | GetElementType | GetType

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