What to do if you have a problem: errors, bugs, corrections and upgrades.

Everyone that uses computers experiences difficulties from time to time. Sometimes, it is because the software they are using really does contain an error or fault (a "bug"), so that it does not work in the way it was supposed to. But very often, there is nothing wrong with the software: the cause of the trouble is how it is being used, or how it was installed. In both cases, human error plays a large part:

Although I will acknowledge and attempt to rectify my mistakes, I do not offer any kind of bespoke (i.e. individual, one-to-one) service for fixing problems with the software. Nor (as explained in the textbook and on the companion CD-ROM) do I or Cambridge University Press provide any kind of warranty regarding my software (see our warranty disclaimer).

Nevertheless, when an error or bug is my fault, I will take reasonable steps to fix it and provide a "bug fix" - an explanation of how to recognise and rectify the problem - on this website. "Reasonable" means that I will devote as much time to solving the problem as I can, taking account of the fact that I have a full time job working for the University of Oxford, and that work on this textbook and course materials is essentially a spare-time activity.

Here is the recipe for fixing a bug, then:

  1. First, let's establish that it really is a bug. Check that you have followed the instructions in the textbook exactly. Common causes of problems include: users typing capital letters where small letters are needed, or vice-versa; punctuation confusions, such as incorrect spaces, the wrong quote symbol (e.g. ` instead of '), - (hyphen) instead of _ (underline) etc.
  2. Similarly, check that the text of the program you are using is correct. For example, if you have edited a copy of one of my programs, perhaps that editing has introduced a mistake. You can check this by copying the original file from the CD-ROM.
  3. If the previous two steps don't solve the problem, it could be that your computer or operating system is not working properly. The simplest check to make in this case is to reboot (i.e. shut down and re-start) your computer.
  4. If you get to this step, it is beginning to appear more likely that there is a fault in the software. Please click on this link to a list of previously reported problems and how to deal with them, and see if the problem you have experienced is among them, and what to do next.

This page last edited on 6/1/04.