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.NET Framework Class Library
Type..::.MakeArrayType Method

Updated: June 2010

Returns a Type object representing a one-dimensional array of the current type, with a lower bound of zero.

Namespace: System
Assembly: mscorlib (in mscorlib.dll)
Syntax
Public Overridable Function MakeArrayType As Type
public virtual Type MakeArrayType()
public:
virtual Type^ MakeArrayType()
abstract MakeArrayType : unit -> Type 
override MakeArrayType : unit -> Type 

Return Value

Type: System..::.Type
A Type object representing a one-dimensional array of the current type, with a lower bound of zero.
Exceptions
ExceptionCondition
NotSupportedException

The invoked method is not supported in the base class. Derived classes must provide an implementation.

TypeLoadException

The current type is TypedReference.

-or-

The current type is a ByRef type. That is, Type..::.IsByRef returns true.

Remarks

The MakeArrayType method provides a way to generate array types whose element types are computed at run time.

Note   The common language runtime makes a distinction between vectors (that is, one-dimensional arrays that are always zero-based) and multidimensional arrays. A vector, which always has only one dimension, is not the same as a multidimensional array that happens to have only one dimension. This method overload can only be used to create vector types, and it is the only way to create a vector type. Use the MakeArrayType(Int32) method overload to create multidimensional array types.

Examples

The following code example creates array, ref (ByRef in Visual Basic), and pointer types for the Test class.


Imports System
Imports System.Reflection
Imports Microsoft.VisualBasic

Public Class Example
    Public Shared Sub Main()
        ' Create a Type object that represents a one-dimensional
        ' array of Example objects.
        Dim t As Type = GetType(Example).MakeArrayType()
        Console.WriteLine(vbCrLf & "Array of Example: " & t.ToString())

        ' Create a Type object that represents a two-dimensional
        ' array of Example objects.
        t = GetType(Example).MakeArrayType(2)
        Console.WriteLine(vbCrLf & "Two-dimensional array of Example: " & t.ToString())

        ' Demonstrate an exception when an invalid array rank is
        ' specified.
        Try
            t = GetType(Example).MakeArrayType(-1)
        Catch ex As Exception
            Console.WriteLine(vbCrLf & ex.ToString())
        End Try

        ' Create a Type object that represents a ByRef parameter
        ' of type Example.
        t = GetType(Example).MakeByRefType()
        Console.WriteLine(vbCrLf & "ByRef Example: " & t.ToString())

        ' Get a Type object representing the Example class, a
        ' MethodInfo representing the "Test" method, a ParameterInfo
        ' representing the parameter of type Example, and finally
        ' a Type object representing the type of this ByRef parameter.
        ' Compare this Type object with the Type object created using
        ' MakeByRefType.
        Dim t2 As Type = GetType(Example)
        Dim mi As MethodInfo = t2.GetMethod("Test")
        Dim pi As ParameterInfo = mi.GetParameters()(0)
        Dim pt As Type = pi.ParameterType
        Console.WriteLine("Are the ByRef types equal? " & (t Is pt))

        ' Create a Type object that represents a pointer to an
        ' Example object.
        t = GetType(Example).MakePointerType()
        Console.WriteLine(vbCrLf & "Pointer to Example: " & t.ToString())
    End Sub

    ' A sample method with a ByRef parameter.
    '
    Public Sub Test(ByRef e As Example)
    End Sub
End Class

' This example produces output similar to the following:
'
'Array of Example: Example[]
'
'Two-dimensional array of Example: Example[,]
'
'System.IndexOutOfRangeException: Index was outside the bounds of the array.
'   at System.RuntimeType.MakeArrayType(Int32 rank) in c:\vbl\ndp\clr\src\BCL\System\RtType.cs:line 2999
'   at Example.Main()
'
'ByRef Example: Example&
'Are the ByRef types equal? True
'
'Pointer to Example: Example*


using System;
using System.Reflection;

public class Example
{
    public static void Main()
    {
        // Create a Type object that represents a one-dimensional
        // array of Example objects.
        Type t = typeof(Example).MakeArrayType();
        Console.WriteLine("\r\nArray of Example: {0}", t);

        // Create a Type object that represents a two-dimensional
        // array of Example objects.
        t = typeof(Example).MakeArrayType(2);
        Console.WriteLine("\r\nTwo-dimensional array of Example: {0}", t);

        // Demonstrate an exception when an invalid array rank is
        // specified.
        try
        {
            t = typeof(Example).MakeArrayType(-1);
        }
        catch(Exception ex)
        {
            Console.WriteLine("\r\n{0}", ex);
        }

        // Create a Type object that represents a ByRef parameter
        // of type Example.
        t = typeof(Example).MakeByRefType();
        Console.WriteLine("\r\nByRef Example: {0}", t);

        // Get a Type object representing the Example class, a
        // MethodInfo representing the "Test" method, a ParameterInfo
        // representing the parameter of type Example, and finally
        // a Type object representing the type of this ByRef parameter.
        // Compare this Type object with the Type object created using
        // MakeByRefType.
        Type t2 = typeof(Example);
        MethodInfo mi = t2.GetMethod("Test");
        ParameterInfo pi = mi.GetParameters()[0];
        Type pt = pi.ParameterType;
        Console.WriteLine("Are the ByRef types equal? {0}", (t == pt));

        // Create a Type object that represents a pointer to an
        // Example object.
        t = typeof(Example).MakePointerType();
        Console.WriteLine("\r\nPointer to Example: {0}", t);
    }

    // A sample method with a ByRef parameter.
    //
    public void Test(ref Example e)
    {
    }
}

/* This example produces output similar to the following:

Array of Example: Example[]

Two-dimensional array of Example: Example[,]

System.IndexOutOfRangeException: Index was outside the bounds of the array.
   at System.RuntimeType.MakeArrayType(Int32 rank) in c:\vbl\ndp\clr\src\BCL\System\RtType.cs:line 2999
   at Example.Main()

ByRef Example: Example&
Are the ByRef types equal? True

Pointer to Example: Example*

 */


using namespace System;
using namespace System::Reflection;

public ref class Example
{
public:
   static void Main()
   {
      // Create a Type object that represents a one-dimensional
      // array of Example objects.
      Type^ t = Example::typeid->MakeArrayType();
      Console::WriteLine( L"\r\nArray of Example: {0}", t );

      // Create a Type object that represents a two-dimensional
      // array of Example objects.
      t = Example::typeid->MakeArrayType( 2 );
      Console::WriteLine( L"\r\nTwo-dimensional array of Example: {0}", t );

      // Demonstrate an exception when an invalid array rank is
      // specified.
      try
      {
         t = Example::typeid->MakeArrayType(  -1 );
      }
      catch ( Exception^ ex ) 
      {
         Console::WriteLine( L"\r\n{0}", ex );
      }

      // Create a Type object that represents a ByRef parameter
      // of type Example.
      t = Example::typeid->MakeByRefType();
      Console::WriteLine( L"\r\nByRef Example: {0}", t );

      // Get a Type object representing the Example class, a
      // MethodInfo representing the "Test" method, a ParameterInfo
      // representing the parameter of type Example, and finally
      // a Type object representing the type of this ByRef parameter.
      // Compare this Type object with the Type object created using
      // MakeByRefType.
      Type^ t2 = Example::typeid;
      MethodInfo^ mi = t2->GetMethod( L"Test" );
      ParameterInfo^ pi = mi->GetParameters()[ 0 ];
      Type^ pt = pi->ParameterType;
      Console::WriteLine( L"Are the ByRef types equal? {0}", (t == pt) );

      // Create a Type object that represents a pointer to an
      // Example object.
      t = Example::typeid->MakePointerType();
      Console::WriteLine( L"\r\nPointer to Example: {0}", t );
   }

   // A sample method with a ByRef parameter.
   //
   void Test( interior_ptr<Example^> /*e*/ )
   {
   }
};

int main()
{
   Example::Main();
}

/* This example produces output similar to the following:

Array of Example: Example[]

Two-dimensional array of Example: Example[,]

System.IndexOutOfRangeException: Index was outside the bounds of the array.
   at System.RuntimeType.MakeArrayType(Int32 rank) in c:\vbl\ndp\clr\src\BCL\System\RtType.cs:line 2999
   at Example.Main()

ByRef Example: Example&
Are the ByRef types equal? True

Pointer to Example: Example*

 */

Version Information

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library
Platforms

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
Change History

Date

History

Reason

June 2010

Added missing TypeLoadException exception.

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