[C++],[быдлокод] Помаленьку учу плюсы (часть 2 из много)

#include <vector>

/*
 * the main class, containing the whole project. Is anything needed here at all?
 */
class project {
  
};

/*
 * class, containing basic data for the project.
 */

class data: public project {
  std::vector <long double> cf_invest;
  std::vector <long double> cf_revenue;
  int length;
  double percent;
public:
  data (); // data input
  long double invest_out (int step);
  long double revenue_out (int step);
  int length_out ();
  double percent_out ();
};

/*
 * class, containing middle calculations
 */

class calculations: public project {
  std::vector <long double> k_discont;
  std::vector <long double> k_inflate;
  std::vector <long double> discont_cf_invest;
  std::vector <long double> discont_cf_revenue;
  std::vector <long double> inflate_cf_revenue;
  std::vector <long double> cf_total;
  std::vector <long double> cf_accumulate;
public:
  calculations (data input_data);
  long double k_discont_out (int step);
  long double k_inflate_out (int step);
  long double discont_cf_invest_out (int step);
  long double discont_cf_revenue_out (int step);
  long double inflate_cf_revenue_out (int step);
  long double cf_total_out (int step);
  long double cf_accumulate_out (int step);
};

/*
 * Class that outputs important project's characteristicks
 */

class output: public project {
  long double profit_index (data input_data, calculations calc_data);
  long double npv (data input_data, calculations calc_data);
  float profit_period (data input_data, calculations calc_data);
  long double ea_calc (data input_data, calculations calc_data);
  long double mirr_calc (data input_data, calculations calc_data);
  long double irr_calc (data input_data, calculations calc_data);
};

/// все одногодовые показатели, что спрашиваются у юзера
class UserInput {
public:
  UserInput() { std::cin >> ...... }
  const double foo;
  const double bar;
};

class YearIndicators { 
public:
  YearIndicators(UserInput user_input, YearIndicators previous_year) {...}
  const double k_discont; 
  const double k_inflate; 
  const double discont_cf_invest; 
  const double discont_cf_revenue; 
  const double inflate_cf_revenue; 
  const double cf_total; 
  const double cf_accumulate;
};