Design by Contract in C++?

An anonymous reader asks: "I have read some of the stuff on Eiffel, watched their tutorial videos about design by contract, and the entire thing sounds like a pretty good idea. However, the problem is that we don't use Eiffel at work, and I highly doubt I could get people to come around to the idea of switching to it. Although we use a lot of C++, I can imagine that a lot of the ideas from Eiffel can be applied there. I have looked around on the net and found a few articles talking about different ways of applying design by contract using assert statements and the like. I also found the dlib C++ library on SourceForge which, among other things, puts a design by contract face on a lot of API calls. So, there are obviously people doing it. What is everyone's experience with Design by Contract in C++? What tools are there that help make it a workable system? Lastly, are there any pitfalls to taking this approach in C++?"