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Marshal.GetIUnknownForObjectInContext Method

Returns an IUnknown interface from a managed object, if the caller is in the same context as that object.

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

[SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags = SecurityPermissionFlag.UnmanagedCode)]
public static IntPtr GetIUnknownForObjectInContext(
	Object o
)

Parameters

o
Type: System.Object

The object whose IUnknown interface is requested.

Return Value

Type: System.IntPtr
The IUnknown pointer for the o parameter, or null if the caller is not in the same context as the specified object.

This method is the same as GetIUnknownForObject except that it returns null if the caller is not in the same context as the object.

NoteNote:

This method uses SecurityAction.LinkDemand to prevent it from being called from untrusted code; only the immediate caller is required to have SecurityPermissionAttribute.UnmanagedCode permission. If your code can be called from partially trusted code, do not pass user input to Marshal class methods without validation. For important limitations on using the LinkDemand member, see Demand vs. LinkDemand.

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

using System;
using System.Runtime.InteropServices;

class Program
{

    static void Run()
    {

        // Create an int object 
        int obj = 1;

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

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

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

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

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

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

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