The conditional compilation directives are used to conditionally include or exclude portions of a source file. This example shows how to use of preprocessor directives like “#define”, “#undef”, “#if”, etc. Firstly, you should add your variables above the “using”.

#define Debug // Debugging on
#undef  Trace // Tracing off

            #if Debug
                //To do something
            #endif

            #if Trace
                //To do someting    
            #endif