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title: "uuid (C++) | Microsoft Docs"
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---
# uuid (C++)
**Microsoft Specific**  
  
 The compiler attaches a GUID to a class or structure declared or defined (full COM object definitions only) with the `uuid` attribute.  
  
## Syntax  
  
```  
  
__declspec( uuid("  
ComObjectGUID  
") ) declarator  
```  
  
## Remarks  
 The `uuid` attribute takes a string as its argument. This string names a GUID in normal registry format with or without the **{ }** delimiters. For example:  
  
```  
struct __declspec(uuid("00000000-0000-0000-c000-000000000046")) IUnknown;  
struct __declspec(uuid("{00020400-0000-0000-c000-000000000046}")) IDispatch;  
```  
  
 This attribute can be applied in a redeclaration. This allows the system headers to supply the definitions of interfaces such as **IUnknown**, and the redeclaration in some other header (such as COMDEF.H) to supply the GUID.  
  
 The keyword [__uuidof](../cpp/uuidof-operator.md) can be applied to retrieve the constant GUID attached to a user-defined type.  
  
 **END Microsoft Specific**  
  
## See Also  
 [__declspec](../cpp/declspec.md)   
 [Keywords](../cpp/keywords-cpp.md)