The C preprocessor

Compile-time constants

#define PI.................... 3.14159 #define MAX_ARRAY_SIZE .....50 #define O_READONLY ..........0x40

Inserting files

#include <stdio.h> ..../* <...> for system include files */ #include "mydefs.h" .../* "..." for local include files */

Conditional compilation

#define DEBUG_ENABLED #ifdef DEBUG_ENABLED ....dump_current_contents_of_data_structure(); #endif

Inline Macros

#define MAX(x,y)........ ( ( (x)>(y) )? (x) : (y) ) #define NEW(x) ..........(x *) malloc(sizeof x) ....best = MAX( one, the_other); ....very_best = MAX( MAX(a,b), c); ....p = NEW(struct listnode);