Well, there's libgd. It's C rather than C++, but it might still be be useful to you.
It might be too low level for your needs because it's rather more general purpose that just for creating charts of specific types. It is often used for this purpose however.
It depends on your requirements.
If high performance is not a requirement you might consider creating a gnuplot script and invoking gnuplot from your program.
You might also want to have a look at some of the sub-projects here: http://www.gnu.org/software/plotutils/