General guidelines for writing portable code

Here are some general guidelines for writing portable code.

• Use functions supported by a major industry standard (such as ABI, POSIX, X/Open).

• When it is necessary to use functions that are not part of a standard, isolate the code in subroutines. It will be easier to rewrite a subroutine when the code is ported than to rewrite functionality that is spread throughout the code.

• Study and resolve compiler and lint(1) warning messages. These tools identify practices that may cause porting problems.

• Avoid hard-coded pathnames, files, directories, or other system-dependent parameters within the code. Use external files or environment variables to read system-dependent data, instead of making hard-coded assumptions.

• Apply internationalization techniques, such as message catalogs and locale environment variables to allow for world-wide usage. Avoid non-portable, hard-coded language features or assumptions about the system's character set.

• Avoid usage of non-standard I/O devices.

• Avoid assumptions about hardware-related parameters, such as the byte length, byte order, word length, or memory alignment.

• Avoid assumptions about how the compiler operates internally; this may vary from platform to platform.