Programming notes

This is a collection of miscellaneous thoughts on coding style recommended for use in our lab.

Editor

1. In general, use Emacs. GNU Emacs for OS X can be downloaded here.
2. In a pinch, use vi. On our Linux systems as well as on OS X, this is actually vim, which offers syntax highlighting. (Note: on OS X, syntax highlighting seems to be disabled by default. Enable it by adding "syntax on" to your ~/.vimrc file.)

Notes on C

1. Don't put multiple commands on a single line. One command per line.
2. I dislike this layout because of its lack of symmetry

   if (i==2) {
           i++;
   }
   

   and think this is cleaner

   if (i==2)
   {
           i++;
   }
   

   However, I've now learned that this is a matter of strong debate, and I definitely defer to Kernighan & Ritchie on this (but strongely side with Stroustrup on the "else" statement). So, given this situation, choose either of these styles, but be consistent.

3. For clarity, I prefer indentations to be 8 spaces (not 4). If you follow this, you'll be in good company. Insert the following snippet in your ~/.emacs file:

   (defconst my-c-style
           '((c-basic-offset       . 8)
             (c-offsets-alist      . ((substatement-open . 0)
                                     )
             )
            )
    "C Style")
   (defun my-c-mode-common-hook ()
           (c-add-style "personal" my-c-style t)
           (setq fill-column 135)
   )
   (add-hook 'c-mode-common-hook 'my-c-mode-common-hook)
   

4. The following is a surprisingly common programming mistake:

   double x, y;
   if (x == y)
   {
           do_something();
   }
   

   You should not test for exact equality between two floating point numbers, since this comparison may fail due to rounding errors. Instead, do:

   #define EPS 1e-9 /* or some other threshold small enough for your purposes */
   
   double x, y;
   if (fabs(x-y) < EPS)
   {
           do_something();
   }