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.
For simple experiments in calculous (changing parameters, seeing graphs of the functions, integrals, and derivatives), you might want to look at the free GeoGebra software package.
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