Macro `cplusplus` Macro `cplusplus` Macro `__cplusplus`

Use Case: Check Compiler Setting Check Compiler Setting

#ifndef __cplusplus
  #error C++ is required
#elif __cplusplus > 199711
  // C++11 (or newer) code goes here
#else
  // old-school code goes here
#endif

ISO Standard Values

C++98	`#define __cplusplus 199711`
C++11	`#define __cplusplus 201103`
C++14	`#define __cplusplus 201402`
C++17	`#define __cplusplus 201703`
C++20	`#define __cplusplus 202002`

Compiler Specifics

Older Compilers

If a compiler was released between C++ standards, values for __cplusplus might differ from the ones in the table above. However, you can always rely on the fact that the value of __cplusplus for a newer standard will be strictly larger than that of the previous standard.

Microsoft Visual Studio (MSVC)

used to use non-standard conforming values
compiler switch /Zc:__cplusplus (as of Visual Studio 2017 version 15.7) makes MSVC use the standard values

GCC (`g++`), Clang (`clang++`)

use mostly standard conforming values for __cplusplus.

Last updated: 2021-04-25