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Type.MakeByRefType Method

Updated: June 2010

Returns a Type object that represents the current type when passed as a ref parameter (ByRef parameter in Visual Basic).

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

public virtual Type MakeByRefType()

Return Value

Type: System.Type
A Type object that represents the current type when passed as a ref parameter (ByRef parameter in Visual Basic).


The invoked method is not supported in the base class.


The current type is TypedReference.


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

The MakeByRefType method provides a way to generate ref types (ByRef in Visual Basic) for parameter lists.

Using the syntax of Microsoft intermediate language (MSIL), if the current Type object represents Int32, this method returns a Type object representing Int32&.

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

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. 
            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*


Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0




June 2010

Added missing TypeLoadException exception.

Customer feedback.