Type.HasElementType-Eigenschaft

Ruft einen Wert ab, der angibt, ob der aktuelle Type einen anderen Typ umfasst oder auf einen anderen Typ verweist, d. h., ob der aktuelle Type ein Array oder ein Zeiger ist oder als Verweis übergeben wird.

Namespace: System
Assembly: mscorlib (in mscorlib.dll)

Syntax

'Declaration
Public ReadOnly Property HasElementType As Boolean
'Usage
Dim instance As Type
Dim value As Boolean

value = instance.HasElementType

public bool HasElementType { get; }

public:
virtual property bool HasElementType {
    bool get () sealed;
}

/** @property */
public final boolean get_HasElementType ()

public final function get HasElementType () : boolean

Eigenschaftenwert

true, wenn Type ein Array oder ein Zeiger ist oder als Verweis übergeben wird, andernfalls false.

Hinweise

Beispielsweise gibt Type.GetType("Int32[]").HasElementType true zurück, wohingegen Type.GetType("Int32").HasElementType false zurückgibt. HasElementType gibt auch für "Int32*" und "Int32&" true zurück.

Wenn der aktuelle Type einen generischen Typ oder einen Typparameter einer generischen Typ- oder Methodendefinition darstellt, gibt diese Eigenschaft immer false zurück.

Beispiel

Im folgenden Beispiel wird in Abhängigkeit davon, ob das Objekt ein Array, ein Verweistyp oder ein Zeiger ist oder nicht, true oder false zurückgegeben.

Imports System
Imports System.Reflection
Imports System.Runtime.InteropServices

Public Class Example

    ' This method is for demonstration purposes.
    Public Shared Sub Test(ByRef x As Integer, <Out> ByRef y As Integer)
    End Sub

    Public Shared Sub Main()
        ' All of the following display 'True'.

        ' Define an array, get its type, and display HasElementType. 
        Dim nums() As Integer = {1, 1, 2, 3, 5, 8, 13}
        Dim t As Type = nums.GetType()
        Console.WriteLine("HasElementType is '{0}' for array types.", t.HasElementType)

        ' Test an array type without defining an array.
        t = GetType(Example())
        Console.WriteLine("HasElementType is '{0}' for array types.", t.HasElementType)

        ' When you use Reflection Emit to emit dynamic methods and
        ' assemblies, you can create array types using MakeArrayType.
        ' The following creates the type 'array of Example'.
        t = GetType(Example).MakeArrayType()
        Console.WriteLine("HasElementType is '{0}' for array types.", t.HasElementType)

        ' When you reflect over methods, HasElementType is true for
        ' ref, out, and pointer parameter types. The following 
        ' gets the Test method, defined above, and examines its
        ' parameters.
        Dim mi As MethodInfo = GetType(Example).GetMethod("Test")
        Dim parms() As ParameterInfo = mi.GetParameters()
        t = parms(0).ParameterType
        Console.WriteLine("HasElementType is '{0}' for ref parameter types.", t.HasElementType)
        t = parms(1).ParameterType
        Console.WriteLine("HasElementType is '{0}' for <Out> parameter types.", t.HasElementType)

        ' When you use Reflection Emit to emit dynamic methods and
        ' assemblies, you can create pointer and ByRef types to use
        ' when you define method parameters.
        t = GetType(Example).MakePointerType()
        Console.WriteLine("HasElementType is '{0}' for pointer types.", t.HasElementType)
        t = GetType(Example).MakeByRefType()
        Console.WriteLine("HasElementType is '{0}' for ByRef types.", t.HasElementType)
    End Sub 

End Class

// This code must be compiled with the /unsafe switch:
//   csc /unsafe source.cs
using System;
using System.Reflection;

public class Example
{
    // This method is for demonstration purposes.
    unsafe public void Test(ref int x, out int y, int* z) 
    { 
        *z = x = y = 0; 
    }

    public static void Main()
    {
        // All of the following display 'True'.

        // Define an array, get its type, and display HasElementType. 
        int[] nums = {1, 1, 2, 3, 5, 8, 13};
        Type t = nums.GetType();
        Console.WriteLine("HasElementType is '{0}' for array types.", t.HasElementType);

        // Test an array type without defining an array.
        t = typeof(Example[]);
        Console.WriteLine("HasElementType is '{0}' for array types.", t.HasElementType);

        // When you use Reflection Emit to emit dynamic methods and
        // assemblies, you can create array types using MakeArrayType.
        // The following creates the type 'array of Example'.
        t = typeof(Example).MakeArrayType();
        Console.WriteLine("HasElementType is '{0}' for array types.", t.HasElementType);

        // When you reflect over methods, HasElementType is true for
        // ref, out, and pointer parameter types. The following 
        // gets the Test method, defined above, and examines its
        // parameters.
        MethodInfo mi = typeof(Example).GetMethod("Test");
        ParameterInfo[] parms = mi.GetParameters();
        t = parms[0].ParameterType;
        Console.WriteLine("HasElementType is '{0}' for ref parameter types.", t.HasElementType);
        t = parms[1].ParameterType;
        Console.WriteLine("HasElementType is '{0}' for out parameter types.", t.HasElementType);
        t = parms[2].ParameterType;
        Console.WriteLine("HasElementType is '{0}' for pointer parameter types.", t.HasElementType);

        // When you use Reflection Emit to emit dynamic methods and
        // assemblies, you can create pointer and ByRef types to use
        // when you define method parameters.
        t = typeof(Example).MakePointerType();
        Console.WriteLine("HasElementType is '{0}' for pointer types.", t.HasElementType);
        t = typeof(Example).MakeByRefType();
        Console.WriteLine("HasElementType is '{0}' for ByRef types.", t.HasElementType);
    }
}

using namespace System;
using namespace System::Reflection;
using namespace System::Runtime::InteropServices;

public ref class Example
{
public:
    // This method is for demonstration purposes. It includes a
    // tracking reference (C# ref, VB ByRef), an out parameter,
    // and a pointer.
    void Test(int% x, [OutAttribute()] int% y, int* z)
    { 
        *z = x = y = 0; 
    }    
};

int main()
{
    // All of the following display 'True'.

    // Define a managed array, get its type, and display HasElementType. 
    array<Example^>^ examples = {gcnew Example(), gcnew Example()};
    Type^ t = examples::typeid; 
    Console::WriteLine(t);
    Console::WriteLine("HasElementType is '{0}' for managed array types.", t->HasElementType);

    // When you use Reflection Emit to emit dynamic methods and
    // assemblies, you can create array types using MakeArrayType.
    // The following creates the type 'array of Example'.
    t = Example::typeid->MakeArrayType();
    Console::WriteLine("HasElementType is '{0}' for managed array types.", t->HasElementType);

    // When you reflect over methods, HasElementType is true for
    // ref, out, and pointer parameter types. The following 
    // gets the Test method, defined above, and examines its
    // parameters.
    MethodInfo^ mi = Example::typeid->GetMethod("Test");
    array<ParameterInfo^>^ parms = mi->GetParameters();
    t = parms[0]->ParameterType;
    Console::WriteLine("HasElementType is '{0}' for ref parameter types.", t->HasElementType);
    t = parms[1]->ParameterType;
    Console::WriteLine("HasElementType is '{0}' for out parameter types.", t->HasElementType);
    t = parms[2]->ParameterType;
    Console::WriteLine("HasElementType is '{0}' for pointer parameter types.", t->HasElementType);

    // When you use Reflection Emit to emit dynamic methods and
    // assemblies, you can create pointer and ByRef types to use
    // when you define method parameters.
    t = Example::typeid->MakePointerType();
    Console::WriteLine("HasElementType is '{0}' for pointer types.", t->HasElementType);
    t = Example::typeid->MakeByRefType();
    Console::WriteLine("HasElementType is '{0}' for ByRef types.", t->HasElementType);
}

import System.*;

public class MyClass
{
} //MyClass

public class Type_HasElementType
{
    public static void main(String[] args)
    {
        try {
            // A nonarray, pointer, or reference element. 
            MyClass myObject1 = new MyClass();
            Object myObject2 = myObject1;

            // Define an array. 
            MyClass myObject3[] = new MyClass[5];
            Object myObject4 = myObject3;
            Object myObjects[] = new Object[] { myObject1, myObject2,
                myObject3, myObject4 };
            Console.WriteLine("\nCheck whether the object is an array, "
                +"a pointer, or a reference type.\n");
            for (int i = 0; i < myObjects.get_Length(); i++) {
                if (myObjects.get_Item(i).GetType().get_HasElementType()) {
                    Console.WriteLine("myObject{0} is an array, pointer, or "
                        +"reference type.", System.Convert.ToString(i));
                }
                else {
                    Console.WriteLine("myObject{0} is not an array, pointer, " 
                        +"or reference type.", System.Convert.ToString(i));
                }
            }
        }
        catch (System.Exception e) {
            Console.WriteLine("Exception: {0} \n", e.get_Message());
        }
    } //main
} //Type_HasElementType

Plattformen

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

.NET Framework unterstützt nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen.

Versionsinformationen

.NET Framework

Unterstützt in: 2.0, 1.1, 1.0

.NET Compact Framework

Unterstützt in: 2.0, 1.0

Siehe auch

Referenz

Type-Klasse
Type-Member
System-Namespace
HasElementTypeImpl
IsArray
IsPointer
IsByRef
GetElementType
GetType