Looking for reference info on #if, #else, #ifdef, #endif, etc

Projects Programming
1

I found info on #define and #include in the reference section but could not find info on #if, #else, #ifdef, #endif, etc
also no sign of PROGMEM reference either...
Is there another reference area that I am missing?

I am trying to understand a sketch but have never run into those commands before so need a little arduino.cc help.

2

Is there another reference area that I am missing?

Google, perhaps ? The terms are not Arduino specific but relate to C and C++

http://www.cplusplus.com/doc/tutorial/preprocessor/