Using System-Specific Include Files

Sometimes platform or release-specific source code differences are large. These differences can be isolated in different #include files and then be referenced by conditional directives.

Here is an example of including 32-bit or 64-bit type definitions depending on the word size of the machine:

#include <limits.h>
#if WORD_BIT > 32
      . . .        /* integers must be 64-bit */
#   include "typedefs_64.h"
#else
       . . .       /* integers must be 32-bit */
#   include "typedefs_32.h"
#endif             /* 32-bit environment */