SnIff++ also purports to present code of any complexity with a friendly, well-labeled interface, and their demo may suffice for purposes of demonstration. It also draws block diagrams where you would not, I think. Visio will too, but it also sucks lymph out of users, and is about the least-free software anywhere. In a pinch, you can simply run lharc5 on the old code and see whether it what its compression ratio is compared to Management Sample Code's. Hence, for 40k blocks of code, 200:1 : 500:1 or 2:5, your code is e^((5/2)-1) times as complex. If you compile using ActiveState's tools, you can just compare binary file sizes! :) Actual complexity needs to be defined in your favorite flavor of formal method! No prototype, no metrics!