=====Preprocessor Commands======

The C++ preprocessor runs before any other compilation happens.  Commands given to the preprocessor allow the programmer to define variables, perform text substitution, and test simple conditions.

|[[sharp|# and ##]]|manipulate strings|
|[[define|#define]]|define macrodefinition|
|[[error|#error]]|display an error message|
|[[preprocessor_if|#if, #ifdef, #ifndef, #else, #elif, and #endif]]|conditional operators|
|[[include|#include]]|insert the contents of another file|
|[[line|#line]]|set line and file information|
|[[pragma|#pragma]]|implementation specific command|
|[[undef|#undef]]|used to undefine macrodefinitions|
|[[preprocessor_vars|Predefined preprocessor variables]]|miscellaneous preprocessor variables|