15. Writing Portable C with GNU Autotools

GNU Autotools permits you to write highly portable programs. However, using GNU Autotools is not by itself enough to make your programs portable. You must also write them portably.

In this chapter we will give an introduction to writing portable programs in C. We will start with some notes on portable use of the C language itself. We will then discuss cross-Unix portability. We will finish with some notes on portability between Unix and Windows.

Portability is a big topic, and we can not cover everything in this chapter. The basic rule of portable code is to remember that every system is in some ways unique. Do not assume that every other system is like yours. It is very helpful to be familiar with relevant standards, such as the ISO C standard and the POSIX.1 standard. Finally, there is no substitute for experience; if you have the opportunity to build and test your program on different systems, do so.