A Blog

Magic Numbers

November 04, 2009

In programming, it is generally a good idea to avoid “magic numbers” meaning a number that could change with requirements:

if (foo < 3) { do something }

That 3 could change, or it’s meaning could be lost. A good practice is to define a variable for that magic number with an intelligent name (and possibly store the number in some configuration).

const int maxWidgets = 3;
if (foo < maxWidgets) { do something }

I did recently see a bit of code that got the concept, but failed in the execution:

const int THREE = 3;
if (foo < THREE) { do something }

It is possible that the maximum number of widgets might change to 10. Then you’re stuck with this brilliant bit of code:

const int THREE = 10;

Uh oh.

Scott Williams

Written by Scott Williams who lives and works in sunny Phoenix, AZ. Twitter is also a place.