If he needs help, help can be provided, particularly in guiding rather than the actual coding itself. Although I don't know what function overloading is and I only program in C (not C++ or C#), I can at least help get started, to some extent. Programming, at its deepest level, is otherwise nothing more than variable manipulation. You'll need to know the formulas for calculating the volume of a cube, cylinder, and cuboid in order to do this task. The cube is the easiest one - I'd recommend starting there. If you can get that to work, then move on to the cuboid. Once that wrks, do the cylinder as well.
I'm all for helping people by providing guidance, but I have no interest in helping someone who baldly asks for their homework to be done for them. There are quite enough people in the IT industry who don't know what they are doing as it is; let's not help more people get bogus qualifications.
At least demonstrate some attempt to solve a problem before just asking others to do it for you. In reality this is a very simple question (including overloading functions) that can be solved by reference to a book on C++. IMO these forums are not a source of one-to-one tuition; if a student is really having that much difficulty with a simple exercise they should be discussing the matter with their tutor.
I'd disagree about programming being merely a question of variable manipulation; much more important (IMO) is the selection of the appropriate way to represent and structure data.