According to MSDN Docs
The volume of a character created with #define is the file in which it was defined.
, , , . - .
Update:
Visual Studio, . . , " ". Configuration Manager (Build- > Configuration Manager)
2:
" ", Visual Studio /define (csc.exe #), , . MSDN csc.exe
/define #define , . #undef . /define, #undef .
, #if, #else, #elif #endif .