Project Flow Generator (for C++)

Hi,
I'm looking for an Open source tool
(not proprietary) thorough which i can make a Data or UML Flow of all the related classes of a Project.Like if I've a folder which contains *.cpp and *.h files. Then is there any tool which can make a Flow diagram.

I've downloaded some of the software's related to it but they aren't giving the desired result.

Please let me know if anyone knows about such tool.

Thanks