AddRef Method
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Marshal.AddRef Method (IntPtr)


Increments the reference count on the specified interface.

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

public static int AddRef(
	IntPtr pUnk


Type: System.IntPtr

The interface reference count to increment.

Return Value

Type: System.Int32

The new value of the reference count on the pUnk parameter.

The common language runtime manages the reference count of a COM object for you, making it unnecessary to use this method directly. In rare cases, such as testing a custom marshaler, you might find it necessary to manipulate an object's lifetime manually. After calling AddRef, you must decrement the reference count by using a method such as Marshal.Release. Do not rely on the return value of AddRef, as it can sometimes be unstable.

You can call Marshal.GetComInterfaceForObject, Marshal.GetIUnknownForObject, or Marshal.GetIDispatchForObject to obtain an IntPtr value that represents an IUnknown interface pointer. You can also use these methods and the AddRef method on managed objects to obtain the COM interfaces represented by the managed object's COM callable wrapper. If you are not familiar with the details of this wrapper type, see COM Callable Wrapper.


requires full trust for the immediate caller. This member cannot be used by partially trusted or transparent code.

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Windows Phone Silverlight
Available since 8.0
Windows Phone
Available since 8.1
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