Property pages are COM objects that implement the `IPropertyPage` or **IPropertyPage2** interface. ATL provides support for implementing property pages through the [ATL Property Page Wizard](../atl/reference/atl-property-page-wizard.md) in the [Add Class dialog box](../ide/add-class-dialog-box.md).

title: "Interfaces (ATL) | Microsoft Docs"

ms.custom: ""

ms.date: "11/04/2016"

ms.technology: ["cpp-atl"]

ms.topic: "reference"

dev_langs: ["C++"]

helpviewer_keywords: ["COM interfaces", "interfaces, COM"]

ms.assetid: de6c8b12-6230-4fdc-af66-a28b91d5ee55

author: "mikeblome"

ms.author: "mblome"

ms.workload: ["cplusplus"]

Each interface is based on the fundamental COM interface, [IUnknown](../atl/iunknown.md). The methods of **IUnknown** allow navigation to other interfaces exposed by the object.

Provides an overview of the Component Object Model's (COM) fundamental concepts, including interfaces, **IUnknown**, reference counting, `QueryInterface`, marshaling, and aggregation.

|**ResourceRegister**|**HRESULT ResourceRegister( LPCOLESTR** *resFileName* **, UINT** `nID` **, LPCOLESTR** `szType` **);**<br /><br /> Registers the script contained in a module's resource. *resFileName* indicates the UNC path to the module itself. `nID` and `szType` contain the resource's ID and type, respectively.|

|**ResourceUnregister**|**HRESULT ResourceUnregister( LPCOLESTR** *resFileName* **, UINT** `nID` **, LPCOLESTR** `szType` **);**<br /><br /> Unregisters the script contained in a module's resource. *resFileName* indicates the UNC path to the module itself. `nID` and `szType` contain the resource's ID and type, respectively.|

|**ResourceRegisterSz**|**HRESULT ResourceRegisterSz( LPCOLESTR** *resFileName* **, LPCOLESTR** *szID* **, LPCOLESTR** `szType` **);**<br /><br /> Registers the script contained in a module's resource. *resFileName* indicates the UNC path to the module itself. *szID* and `szType` contain the resource's string identifier and type, respectively.|

|**ResourceUnregisterSz**|**HRESULT ResourceUnregisterSz( LPCOLESTR** *resFileName* **, LPCOLESTR** *szID* **, LPCOLESTR** `szType` **);**<br /><br /> Unregisters the script contained in a module's resource. *resFileName* indicates the UNC path to the module itself. *szID* and `szType` contain the resource's string identifier and type, respectively.|

title: "IUnknown Implementation Classes (ATL) | Microsoft Docs"

ms.custom: ""

ms.date: "11/04/2016"

ms.technology: ["cpp-atl"]

ms.topic: "reference"

f1_keywords: ["vc.atl.Iunknown"]

dev_langs: ["C++"]

helpviewer_keywords: ["IUnknown implementation classes"]

ms.assetid: 47b69bb5-69d8-4a9c-84a8-329bdde2bb3f

author: "mikeblome"

ms.author: "mblome"

ms.workload: ["cplusplus"]

The following classes implement **IUnknown** and related methods:

- [CComAggObject](../atl/reference/ccomaggobject-class.md) Implements **IUnknown** for an aggregated object.

- [CComObject](../atl/reference/ccomobject-class.md) Implements **IUnknown** for a nonaggregated object.

- [CComPolyObject](../atl/reference/ccompolyobject-class.md) Implements **IUnknown** for aggregated and nonaggregated objects. Using `CComPolyObject` avoids having both `CComAggObject` and `CComObject` in your module. A single `CComPolyObject` object handles both aggregated and nonaggregated cases.

- [CComObjectNoLock](../atl/reference/ccomobjectnolock-class.md) Implements **IUnknown** for a nonaggregated object, without modifying the module lock count.

- [CComTearOffObject](../atl/reference/ccomtearoffobject-class.md) Implements **IUnknown** for a tear-off interface.

- [CComCachedTearOffObject](../atl/reference/ccomcachedtearoffobject-class.md) Implements **IUnknown** for a "cached" tear-off interface.

- [CComContainedObject](../atl/reference/ccomcontainedobject-class.md) Implements **IUnknown** for the inner object of an aggregation or a tear-off interface.

- [CComObjectStack](../atl/reference/ccomobjectstack-class.md) Creates a temporary COM object, using a skeletal implementation of **IUnknown**.

If you statically link to the CRT, code from the CRT is placed in your executable image and you do not need to have the CRT DLL present on a system to run your image. If you dynamically link to the CRT, references to the code in the CRT DLL are placed in your image, but not the code itself. In order for your image to run on a given system, the CRT DLL must be present on that system. Even when you dynamically link to the CRT, you may find that some code can be statically linked (for example, **DllMainCRTStartup**).

When you link your image, you either explicitly or implicitly specify an entry point that the operating system will call into after loading the image. For a DLL, the default entry point is **DllMainCRTStartup**. For an EXE, it is **WinMainCRTStartup**. You can override the default with the /ENTRY linker option. The CRT provides an implementation for **DllMainCRTStartup**, **WinMainCRTStartup**, and **wWinMainCRTStartup** (the Unicode entry point for an EXE). These CRT-provided entry points call constructors on global objects and initialize other data structures that are used by some CRT functions. This startup code adds about 25K to your image if it is linked statically. If it is linked dynamically, most of the code is in the DLL, so your image size stays small.