The agony and the ecstasy of debugging

If you have ever written a computer program with any degree of seriousness then you will know the feeling: your heart sinking as you realise what you thought was a perfectly good piece of code has a bug somewhere less than obvious.

In my case this has happened twice in a week and both times has meant the work I had done as part of my PhD has had to start again (not all of it, obviously, but this, most recent bit). Yesterday evening’s realisation was particularly annoying because it came after I had sent my supervisor an email suggesting I had some quite interesting and counter-intuitive results to share.

Since then I had spent quite a few hours trying to work out what on Earth was wrong – debugging assembly is not complex in the sense that most instructions do simple things – but it also reminds you of the essential state-machine-nature of a general computing device: there are lots of things to track.

Of course, that also brings pleasure – there is no point in denying that solving these problem is one of the truly engaging things about computing.

Job is done now and I am once again collecting results and hoping that I do not spot another flaw.