Login | Register   
RSS Feed
Download our iPhone app
Browse DevX
Sign up for e-mail newsletters from DevX

By submitting your information, you agree that devx.com may send you DevX offers via email, phone and text message, as well as email offers about other products and services that DevX believes may be of interest to you. DevX will process your information in accordance with the Quinstreet Privacy Policy.

Tip of the Day
Home » Tip Bank » C++
Language: C++
Expertise: All
Sep 23, 1999



Building the Right Environment to Support AI, Machine Learning and Deep Learning

Give Meaningful Names to Magic Numbers

"Magic numbers" are arbitrary constant values that indicate array bounds, maximal number of open files, the size of a memory page, and similar environment and program-specific units. Instead of using hard-coded values of magic numbers, it's better to use a named constant. Consider the following example:
  ioctl(fd, KIOCSOUND, 1193180/hertz); //make a beep
The magical value 1193180 happens to be the number of clock cycles per second on this particular machine. However, readers of this code have no way of guessing what this magic number represents. Furthermore, the use of a hard-coded literal value also compromises code portability since on another machine, the number of clock cycles is likely to be different.

The preferred method of handling magic numbers is to give them a meaningful name, which is both more readable and easier to maintain:

  const int CLOCK _CYCLES = 1193180;
  ioctl(fd, KIOCSOUND, CLOCK _CYCLES /hertz);
When this code is ported to another machine, only the definition of CLOCK_CYCLES should change.
Danny Kalev
Comment and Contribute






(Maximum characters: 1200). You have 1200 characters left.



Thanks for your registration, follow us on our social networks to keep up-to-date