#defines are EVIL (part II)

In a previous post I discussed some aspects of the C preprocessor (hereafter the CPP) that are evil. Turns out that this week, I had another problem related to a bad usage of the CPP. It didn’t take long to fix, but I can understand why it could be long to figure out.

And while the bug was caused by a careless use of the CPP, I think there’s a couple of simple things we can do to help avoid these.

Foiled!

QuickSort, due to Hoare, is one of the best comparison-based sorting algorithms around. There are a number of variations, but the vanilla QuickSort does a great job… most of the times.

Indeed, there are occasions where QuickSort leaves its expected run-time to reach run-time, its worst case. But what does it take to push QuickSort into its worst behaviour?

#defines are EVIL

The C (and C++) preprocessor is a powerful but dangerous tool. For sure, it helps with a number of problems, from conditional code inclusion to explicit code generation, but it has a few problems. In fact, more than a few. It is evil.

The C preprocessor (hereafter CPP) should be used with extreme care. For one thing, the CPP doesn’t know about the language it is applied on, it merely proceeds to the translation of the input using very simple rules, and this can leads to tons of hard to detect—and to fix—problems.