Function main

Exercises/NoModules/Chapter 20/Soln20_03/Soln20_03.cpp:24–80

#include <utility>

int main()
{
  std::string text;                                // Stores input prose or poem
  std::cout << "Enter a poem or prose over one or more lines.\n"
            << "Terminate the input with #:\n";
  getline(std::cin, text, '#');

  std::map<char, std::vector<std::string>> lists;
  
  // Extract words and store in the appropriate list
  const std::string_view separators {" \n\t,.\"?!;:"}; // Separators between words
  size_t start {};                                 // Start of a word
  size_t end {};                                   // separator position after a word
  while (std::string::npos != (start = text.find_first_not_of(separators, start)))
  {
    end = text.find_first_of(separators, start+1);
    const auto word{ text.substr(start, end - start) };
    const auto letter{ static_cast<char>(std::toupper(word[0])) };
    lists[letter].push_back(word);
    start = end;
  }

  // List the words in order 5 to a line
  const size_t perline {5};
  
  /* Option 1: use a loop similar to the original one */
  const std::string_view letters{ "ABCDEFGHIJKLMNOPQRSTUVWXYZ" };
  for (char letter : letters)
  {
    if (!lists.contains(letter))
      continue;
  
    size_t count {};                               // Word counter
    for (const auto& word : lists[letter])
    {
      if (count++ % perline == 0 && count != 1)
        std::cout << std::endl;
      std::cout << word << ' ';
    }
    std::cout << std::endl;
  }

  std::cout << std::endl;

  /* Option 2: take advantage of the fact that the keys are already sorted in the map */
  for (const auto& [letter, list] : lists)
  {
    size_t count{};                               // Word counter
    for (const auto& word : list)
    {
      if (count++ % perline == 0 && count != 1)
        std::cout << std::endl;
      std::cout << word << ' ';
    }
    std::cout << std::endl;
  }
}