14.1. C Language Portability
The C language makes it easy to write non-portable code. This section discusses these portability issues, and how to avoid them.
This discussion concentrates on differences that can arise on systems in common use today. For example, all common systems today define char to be 8 bits, and define a pointer to hold the address of an 8-bit byte. This examination does not discuss the more exotic possibilities found on historical machines or on certain supercomputers. If your program needs to run in unusual settings, make sure you understand the characteristics of those systems; the system documentation should include a C portability guide describing the problems you are likely to encounter.
14.1.1. ISO C
The ISO C standard ...