Keywords are predefined reserved identifiers that have special meanings. They cannot be used as identifiers in your program. The following keywords are reserved for C++:
Syntax
keyword: one of
| asm1 | auto | bad_cast | bad_typeid |
| bool | break | case | catch |
| char | class | const | const_cast |
| continue | default | delete | do |
| double | dynamic_cast | else | enum |
| except | explicit | extern | false |
| finally | float | for | friend |
| goto | if | inline | int |
| long | mutable | namespace | new |
| operator | private | protected | public |
| register | reinterpret_cast | return | short |
| signed | sizeof | static | static_cast |
| struct | switch | template | this |
| throw | true | try | type_info |
| typedef | typeid | typename | union |
| unsigned | using | virtual | void |
| volatile | while |
1 Reserved for compatibility with other C++ implementations, but not implemented. Use __asm.
Microsoft Specific
In Microsoft C++, identifiers with two leading underscores are reserved for compiler implementations. Therefore, the Microsoft convention is to precede Microsoft-specific keywords with double underscores. These words cannot be used as identifier names.
| allocate3 | __inline | property3 |
| __asm1 | __int8 | selectany3 |
| __based2 | __int16 | __single_inheritance |
| __cdecl | __int32 | __stdcall |
| __declspec | __int64 | thread3 |
| dllexport3 | __leave | __try |
| dllimport3 | __multiple_inheritance | uuid3 |
| __except | naked3 | __uuidof |
| __fastcall | nothrow3 | __virtual_inheritance |
| __finally |
1 Replaces C++ asm syntax.
2 The __based keyword has limited uses for 32-bit target compilations.
3 These are special identifiers when used with __declspec; their use in other contexts is not restricted.
Microsoft extensions are enabled by default. To ensure that your programs are fully portable, you can disable Microsoft extensions by specifying the ANSI-compatible /Za command-line option (compile for ANSI compatibility) during compilation. When you do this, Microsoft-specific keywords are disabled.
When Microsoft extensions are enabled, you can use the previously-listed keywords in your programs. For ANSI compliance, these keywords are prefaced by a double underscore. For backward compatibility, single-underscore versions of all the keywords except __except, __finally, __leave, and __try are supported. In addition, __cdecl is available with no leading underscore.
END Microsoft Specific