C++ static_cast to double type

#include <iostream>
#include <iomanip>

int main(){/*  w ww .  j a  v  a2s . c o  m*/
  const double lbs_per_kg {2.2};
  const double inches_per_foot {12.0};
  const double meters_per_foot {0.3048};
  double w_lbs {};
  unsigned int h_feet {};
  unsigned int h_inches {};

  std::cout << "Enter your weight in pounds: ";
  std::cin >> w_lbs;
  std::cout << "Enter you height in feet and inches: ";
  std::cin >> h_feet >> h_inches;

  double w_kg {w_lbs/lbs_per_kg};

  double h_meters {};

  h_meters = meters_per_foot*(static_cast<double>(h_feet) + h_inches/inches_per_foot);

  double bmi {w_kg / (h_meters*h_meters)};

  std::cout << "Your BMI is " << std::fixed << std::setprecision(1) << bmi << std::endl;
}