For maximum portability, all code should conform to ANSI/ISO C89 (C99 is not yet well-supported enough to be portable). Prototypes should always be provided for all functions (we don’t attempt to be friendly to pre-ANSI C compilers; there are just too many unknowns).

Adding small platform-specific features (such as using abort instead of exit on fatal errors) is allowed, but the functionality should be checked for using autoconf. Major platform-specific features should be avoided unless the functionality can be emulated on all platforms. Path and directory searches for header files fall into this latter category.

Functions which are standard in some environments but not strictly ANSI C (such as strdup and strcasecmp) should be checked for using autoconf and functionally identical replacements included in the package.

A small set of allocation replacements are provided that do internal allocation failure (NULL return) checks. These are named identically to the functions they replace, with a prepended “x”. E.g. xstrdup, xmalloc, etc. These functions should be used instead of the corresponding standard C library functions in order to maintain standardized error checking and messages for all memory allocation.