C++ in a Nutshell

The #error directive tells the preprocessor to issue an error message and mark the source file as ill- formed , just as if the programmer made a programming error that the compiler detected . You can supply any sequence of preprocessor tokens as the message , and those tokens are echoed in the error message.

Example

#if !defined(_ _cplusplus) (_ _cplusplus < 199711L) #error Not a conforming C++ compiler. #endif

See Also

#line directive