Function from_roman

Examples/Modules/Chapter 11/Ex11_05/from_roman.cpp:5–15

import :internals;

unsigned int from_roman(std::string_view roman)
{
  unsigned int result{};
  for (size_t i{}, n{ roman.length() }; i < n; ++i)
  {
    const auto j{ from_roman(roman[i]) };   // Integer value of the i'th roman digit
    // Look at the next digit (if there is one) to know whether to add or subtract j
    if (i + 1 == n || j >= from_roman(roman[i + 1])) result += j; else result -= j;
  }
  return result;
}