3. Preprocessor Examples

#include <stdio.h>

#ifdef unix
# include <unistd.h>
#else
# include <cygwin.h>
#endif

#include "myheader.h"

#define NMAX 100  /* K&R style comment */

#define SQR(x) ((x)*(x)) // C++ style comment

/* Comments do not nest */

/*
 * K&R style comments can span
 *  more than one line.
 */