#pragma message( messagestring )
Sends a string literal to the standard output without terminating the compilation. A typical use of the message pragma is to display informational messages at compile time.
The following code fragment uses the message pragma to display a message during compilation:
#if _M_IX86 == 500
#pragma message( "Pentium processor build" )
#endif
The messagestring parameter can be a macro that expands to a string literal, and you can concatenate such macros with string literals in any combination. For example, the following statements display the name of the file being compiled and the date and time when the file was last modified:
#pragma message( "Compiling " __FILE__ )
#pragma message( "Last modified on " __TIMESTAMP__ )