The #error Conditional Directive

The #error directive takes a string as an argument and produces an error message at compile-time. Errors produced by this directive are displayed as normal compiler errors.

Like the #warning directive, this directive is most useful for detecting pre-defined constraints and inconsistencies during preprocessing of the source file.

Syntax

#error <message string>

The message string identifier shown above indicates the error message to be displayed. The following example illustrates use of the #error directive:

    #if DEBUG 
        ...
    #elif RETAIL
        ...
    #else
       #error DEBUG or RETAIL must be defined!
    #endif

When the error above is encountered, the following line will be output:

    #error 'DEBUG or RETAIL must be defined' (J0500)