Generating UML from C++ code?

Here are a few options:

Step-by-Step Guide to Reverse Engineering Code into UML Diagrams with Microsoft Visio 2000 - http://msdn.microsoft.com/en-us/library/aa140255(office.10).aspx

BoUML - http://bouml.fr/features.html

StarUML - http://staruml.sourceforge.net/en/

Reverse engineering of the UML class diagram from C++ code in presence of weakly typed containers (2001) - http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.27.9064

Umbrello UML Modeller - http://uml.sourceforge.net/

A list of other tools to look at - http://plg.uwaterloo.ca/~migod/uml.html

If its just diagrams that you want, doxygen does a pretty good job.

I believe Enterprise Architect can do that.

UML Studio does this quite well in my experience, and will run in "freeware mode" for small projects.

Whoever wants UML deserves Rational Rose :)

StarUML does just that and it is free. Unfortunately it hasn't been updated for a while. There were a couple of offshoot projects (as the project admins wouldn't allow it to be taken over) but they too have died a death.