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The latest version of this topic can be found at #error Directive (C/C++). The #error directive emits a user-specified error message at compile time and then terminates the compilation.
Syntax
#errortoken-string
Remarks
The error message that this directive emits includes the token-string parameter. The token-string parameter is not subject to macro expansion. This directive is most useful during preprocessing for notifying the developer of a program inconsistency or the violation of a constraint. The following example demonstrates error processing during preprocessing:
#if !defined
(__cplusplus)
#error C++ compiler required.
#endif