17.2 Windows versus UNIX

When writing samples and prototype code and even production applications, keep in mind that different UNIX implementations and Windows 95/NT have different APIs, provide different system services, and can even provide substantially different development environments (such as contents of include files, location of libraries, etc.). Here are a few things to look out for when writing a program under UNIX with the intent to port to Windows:

• Avoid the identifiers near and far, which are reserved words in most Windows compilers. Common replacements are nnear and ffar.
• The math constant M_PI isn't provided by at least one Win32 development environment. You may find adding the following code after #include <math.h> to be helpful:

  	#ifndef M_PI
  	#define M_PI 3.14159265358979323846
  	#endif

• Do not #include <unistd.h>, as it contains UNIX-specific definitions. At the very least, check with your Windows environment before using functions or constants from unistd.
• The constants EXIT_SUCCESS and EXIT_FAILURE may not be available. You could include code to define these constants similar to the above code for M_PI.
• Single-precision versions of trigonometric functions such as sinf and cosf while desirable for performance may not be available on all platforms.

A more in-depth list of portability considerations is available in the file Portability.txt in the GLUT 3.6 distribution. GLUT is described in more detail in Section 19.