I sympathize, but can't help with a sensible (and somewhat concrete) answer unless you provide some more context. What specifically makes it hard ? The calculus, the c++ language, anything else ... ?
What have you done/seen/learnt so far ?
If you are instead trying to learn Calculus and want to use programming to verify your answers (not a good idea - as you'll be spinning your wheels and getting frustrated trying to understand why your answer isn't what the teacher gets exactly - and it wont help on tests or quizzes).
You could consider using MATLAB (popular in college with engineers) or Mathematica:
While you can use C++ for any problem that is or can get computable, you will definitely need some good skills in C++ first. In the past when in college, I was using C extensively for computations in various fields of math. It was an excellent exercise for becoming a better programmer. You can also do this in C++ - provided that you use the available well written and tested libraries that exist, but it will be tricky enough when it comes to difficult concepts / computations. I would recommend to try to do your best - it will take time and efforts, but meanwhile, as pointed out by jedishrfu, you can use some numerical computing environment like Matlab or Mathematica - there is other such software as well, in order to learn the math concepts without inaccurate approximations or other errors.