Type.HasElementType 属性
获取一个值，通过该值指示当前 Type 是包含还是引用另一类型，即当前 Type 是数组、指针还是通过引用传递。
**命名空间:**System
**程序集:**mscorlib（在 mscorlib.dll 中）
语法
声明
Public ReadOnly Property HasElementType As Boolean
用法
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
属性值
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[]").HasElementType 返回 true，而 Type.GetType("Int32").HasElementType 返回 false。对于“Int32*”和“Int32&”，HasElementType 也返回 true。
如果当前 Type 表示泛型类型，或泛型类型或泛型方法的定义中的类型参数，则此属性始终返回 false。
示例
下面的示例根据对象是否是数组、引用类型或指针来返回 true 或 false。
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
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
HasElementTypeImpl
IsArray
IsPointer
IsByRef
GetElementType
GetType