---
title: "ActivateInstance Function | Microsoft Docs"
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ms.date: "11/04/2016"
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ms.technology: ["cpp-windows"]
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f1_keywords: ["client/Windows::Foundation::ActivateInstance", "client/ABI::Windows::Foundation::ActivateInstance"]
dev_langs: ["C++"]
helpviewer_keywords: ["ActivateInstance function"]
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author: "mikeblome"
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---
# ActivateInstance Function
Registers and retrieves an instance of a specified type defined in a specified class ID.  
  
## Syntax  
  
```  
template<  
   typename T  
>  
inline HRESULT ActivateInstance(  
   _In_ HSTRING activatableClassId,  
   _Out_ Microsoft::WRL::Details::ComPtrRef<T> instance  
);  
```  
  
#### Parameters  
 `T`  
 A type to activate.  
  
 `activatableClassId`  
 The name of the class ID that defines parameter `T`.  
  
 `instance`  
 When this operation completes, a reference to an instance of `T`.  
  
## Return Value  
 S_OK if successful; otherwise, an error HRESULT that indicates the cause of the error.  
  
## Requirements  
 **Header:** client.h  
  
 **Namespace:** Windows::Foundation  
  
## See Also  
 [Windows::Foundation Namespace](../windows/windows-foundation-namespace.md)