I can give you an example program that analyses C++ code. It has as input a tags file and a bunch of C++ code. And it generates a bunch of html files showing the class hierachy and the complexity off all classes. It does this in three steps:

1. It parses the tagsfile to figure out where to find all the classes and operations in the code, and to build the class tree. This uses a fair amount of regular expressions and a couple of functions that recursively walks through a hashes and arrays.
2. It scans the c++ source files to figure out how many lines of code there are per operation and class. The results are later used to sort the classes according to complexity.
3. It transforms the results into html files.

The code has not been optimized, and I think there probably plenty of stuff to optimize. It has about 20 subs. It was written when I just started programming in Perl, so it probably can also be used to show how to improve style and programming techniques.

You would need to have a fair amount of C++ code to analyse and access to a ctags program. In addition, the C++ code should not use any namespaces.

Have Fun