#ifdef Considered Harmful, or Portability Experience with C News

We believe that a C programmer's impulse to use #ifdef in an attempt at portability is usually a mistake. Portability is generally the result of advance planning rather than trench warfare involving #ifdef. In the course of developing C News on different systems, we evolved various tactics for dealing with differences among systems without producing a welter of #ifdef at points of difference. We discuss the alternatives to, and occasional proper use of, #ifdef.