Isolating System-Specific Code

Use conditional directives to isolate sections of platform or release-specific code. This is useful when the number of lines of release or platform-specific source code is small in relation to the number of lines of common code. You could, for example, encapsulate code that is different between the 32-bit and 64-bit HP-UX with conditional directives.

The following example uses a #define macro within a conditional directive:

#ifdef __LP64__
   . . .     /* LP64 specific code goes here */
#else
   . . .     /* ILP32 specific code goes here */
#endif
   . . .     /* Code common to both platforms  goes here */