The #ifdef directive controls conditional compilation of the resource file by checking the specified name. If the name has been defined by using a #define directive or by using the /d command-line option with the resource compiler, #ifdef directs the compiler to continue with the statement immediately after the #ifdef directive. If the name has not been defined, #ifdef directs the compiler to skip all statements up to the next #endif directive.
Name to be checked by the directive.
This example compiles the BITMAP statement only if Debug is defined:
#ifdef Debug BITMAP 1 errbox.bmp #endif