---
title: "Microsoft Extensions"
ms.date: "11/04/2016"
helpviewer_keywords: ["Microsoft extensions to C/C++"]
ms.assetid: 68654516-24ef-4f33-aae2-175f86cc1979
---
# Microsoft Extensions

*asm-statement*:<br/>
&nbsp;&nbsp;&nbsp;&nbsp;**__asm**  *assembly-instruction* **;**<sub>opt</sub><br/>
&nbsp;&nbsp;&nbsp;&nbsp;**__asm {**  *assembly-instruction-list*  **} ;**<sub>opt</sub>

*assembly-instruction-list*:<br/>
&nbsp;&nbsp;&nbsp;&nbsp;*assembly-instruction* **;**<sub>opt</sub> <br/>
&nbsp;&nbsp;&nbsp;&nbsp;*assembly-instruction* **;** *assembly-instruction-list* **;**<sub>opt</sub>

*ms-modifier-list*:<br/>
&nbsp;&nbsp;&nbsp;&nbsp;*ms-modifier* *ms-modifier-list*<sub>opt</sub>

*ms-modifier*:<br/>
&nbsp;&nbsp;&nbsp;&nbsp;**__cdecl**<br/>
&nbsp;&nbsp;&nbsp;&nbsp;**__fastcall**<br/>
&nbsp;&nbsp;&nbsp;&nbsp;**__stdcall**<br/>
&nbsp;&nbsp;&nbsp;&nbsp;**__syscall** (reserved for future implementations)<br/>
&nbsp;&nbsp;&nbsp;&nbsp;**__oldcall** (reserved for future implementations)<br/>
&nbsp;&nbsp;&nbsp;&nbsp;**__unaligned** (reserved for future implementations)<br/>
&nbsp;&nbsp;&nbsp;&nbsp;*based-modifier*

*based-modifier*:<br/>
&nbsp;&nbsp;&nbsp;&nbsp;**__based (** *based-type* **)**

*based-type*:<br/>
&nbsp;&nbsp;&nbsp;&nbsp;*name*