Function main

Exercises/NoModules/Chapter 09/Soln9_04.cpp:14–27

std::optional<std::string> largest(std::span<const std::string> words);

int main()
{
  const double array[]{ 1.5, 44.6, 13.7, 21.2, 6.7 };
  const std::vector numbers{ 15, 44, 13, 21, 6, 8, 5, 2 };
  const std::vector data{ 3.5, 5.0, 6.0, -1.2, 8.7, 6.4 };
  const std::array array_data{ 3.5, 5.0, 6.0, -1.2, 8.7, 6.4 }; // Throwing in an std::array for good measure
  const std::vector<std::string> names{ "Charles Dickens", "Emily Bronte",
                                  "Jane Austen", "Henry James", "Arthur Miller" };
  std::cout << "The largest of array is " << *largest(array) << std::endl;            // Crashes if nullopt is returned
  std::cout << "The largest of numbers is " << largest(numbers).value() << std::endl; // Throws exception (see Chapter 16) for nullopt
  std::cout << "The largest of data is " << largest(data).value() << std::endl;
  std::cout << "The largest of array_data is (also) " << *largest(array_data) << std::endl;
  std::cout << "The largest of names is " << largest(names).value_or("<null>") << std::endl;
}

// Finds the largest of a span of values
std::optional<double> largest(std::span<const double> data)