Changes

* Pre-Processor Directives (Compiler continued) !* Macros !*: #define, #undef !*: multi-line macros !* Conditional Compilation !*: #ifdef, #ifndef, #if, #elif, #else, #endif, #undef !* Header file safeguards !*: non-standard: #pragma once, !

*: sizeof*: Integer, floating point, void, pointer, enum

*: auto, register, volatile, const, * Statics* extern* typedef