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Marshal.GetIUnknownForObject(Object) Method

  • Reference

Definition

Namespace:
System.Runtime.InteropServices
Assembly:
System.Runtime.InteropServices.dll
Assembly:
mscorlib.dll
Assembly:
netstandard.dll
Source:
Marshal.NoCom.cs
Source:
Marshal.NoCom.cs
Source:
Marshal.NoCom.cs

Returns an IUnknown interface from a managed object.

public:
 static IntPtr GetIUnknownForObject(System::Object ^ o);
[System.Security.SecurityCritical]
public static IntPtr GetIUnknownForObject (object o);
[System.Runtime.Versioning.SupportedOSPlatform("windows")]
public static IntPtr GetIUnknownForObject (object o);
public static IntPtr GetIUnknownForObject (object o);
[<System.Security.SecurityCritical>]
static member GetIUnknownForObject : obj -> nativeint
[<System.Runtime.Versioning.SupportedOSPlatform("windows")>]
static member GetIUnknownForObject : obj -> nativeint
static member GetIUnknownForObject : obj -> nativeint
Public Shared Function GetIUnknownForObject (o As Object) As IntPtr

Parameters

o
Object

The object whose IUnknown interface is requested.

Returns

IntPtr

nativeint

The IUnknown pointer for the o parameter.

Attributes
SecurityCriticalAttribute SupportedOSPlatformAttribute

Examples

The following example demonstrates how to retrieve an IUnknown interface for a managed object using the GetIUnknownForObject method.

using System;
using System.Runtime.InteropServices;

class Program
{

    static void Run()
    {

        // Create an int object
        int obj = 1;

        Console.WriteLine("Calling Marshal.GetIUnknownForObject...");

        // Get the IUnKnown pointer for the Integer object
        IntPtr pointer = Marshal.GetIUnknownForObject(obj);

        Console.WriteLine("Calling Marshal.Release...");

        // Always call Marshal.Release to decrement the reference count.
        Marshal.Release(pointer);
    }

    static void Main(string[] args)
    {
        Run();
    }
}

Imports System.Runtime.InteropServices

Module Program


    Sub Run()

        ' Dim an Integer object
        Dim IntegerObject As Integer = 1

        ' Dim a pointer
        Dim pointer As IntPtr

        Console.WriteLine("Calling Marshal.GetIUnknownForObject...")

        ' Get the IUnKnown pointer for the Integer object
        pointer = Marshal.GetIUnknownForObject(IntegerObject)

        Console.WriteLine("Calling Marshal.Release...")

        ' Always call Marshal.Release to decrement the reference count.
        Marshal.Release(pointer)



    End Sub

    Sub Main(ByVal args() As String)

        Run()

    End Sub

End Module

Remarks

In managed code, you seldom work directly with the IUnknown interface. However, GetIUnknownForObject is useful when calling a method that exposes a COM object parameter as an IntPtr type, or with custom marshaling. Calling an object with this method causes the reference count to increment on the interface pointer before the pointer is returned. Always use Marshal.Release to decrement the reference count once you have finished with the pointer. This method provides the opposite functionality of the Marshal.GetObjectForIUnknown method.

You can also use this method on a managed object to obtain an interface pointer to the COM Callable Wrapper for the object.

Applies to

See also