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# PFAuthenticationLoginWithFacebookGetResultSize

> Get the size in bytes needed to store the result of a PFAuthenticationLoginWithFacebookAsync call.

Get the size in bytes needed to store the result of a PFAuthenticationLoginWithFacebookAsync call.

## Syntax

```cpp theme={null}
HRESULT PFAuthenticationLoginWithFacebookGetResultSize(  
    XAsyncBlock* async,  
    size_t* bufferSize  
)  
```

### Parameters

**`async`**   XAsyncBlock\*<br />*Inout*

XAsyncBlock for the async operation.

**`bufferSize`**   size\_t\*<br />*output*

The buffer size in bytes required for the result.

### Return value

Type: HRESULT

Result code for this API operation. If the service call is unsuccessful, the result will be E\_PF\_ENCRYPTION\_KEY\_MISSING, E\_PF\_EVALUATION\_MODE\_PLAYER\_COUNT\_EXCEEDED, E\_PF\_FACEBOOK\_API\_ERROR, E\_PF\_INVALID\_FACEBOOK\_TOKEN, E\_PF\_PLAYER\_SECRET\_ALREADY\_CONFIGURED, E\_PF\_PLAYER\_SECRET\_NOT\_CONFIGURED, E\_PF\_REQUEST\_VIEW\_CONSTRAINT\_PARAMS\_NOT\_ALLOWED or any of the global PlayFab Service errors. See doc page "Handling PlayFab Errors" for more details on error handling.

## Requirements

**Header:** PFAuthentication.h

## See also

[PFAuthentication members](/services/playfab/api-references/c/pfauthentication/pfauthentication_members)


## Related topics

- [Services C API overview - PFAuthentication.h](/services/playfab/api-references/c/pfauthentication/pfauthentication_members.md)
- [PFAuthenticationLoginWithFacebookGetResult](/services/playfab/api-references/c/pfauthentication/functions/pfauthenticationloginwithfacebookgetresult.md)
- [PFAuthenticationLoginWithPSNGetResultSize](/services/playfab/api-references/c/pfauthentication/functions/pfauthenticationloginwithpsngetresultsize.md)
- [PFAuthenticationLoginWithSteamGetResultSize](/services/playfab/api-references/c/pfauthentication/functions/pfauthenticationloginwithsteamgetresultsize.md)
- [PFAuthenticationLoginWithXboxGetResultSize](/services/playfab/api-references/c/pfauthentication/functions/pfauthenticationloginwithxboxgetresultsize.md)