C251 User's Guide

#message

The #message directive causes the preprocessor to emit a message in the listing file. The rest of the line is the message.

#message "message"

You may use #message inside a condition that detects a condition you wish to annotate. For example, the following outputs a message if MYCODE is not defined.

#ifndef MYCODE
#message "This code will not work without the Keil Compiler."
#endif