Function main

Exercises/NoModules/Chapter 07/Soln7_09B.cpp:7–64

#include <cctype>

int main()
{
  std::string text;      // The text to be checked
  std::cout << "Enter some text terminated by *:\n";
  std::getline(std::cin, text, '*');

  const auto whitespace{ " \t\n\r\f\v" };  // Can be solved using std::isspace() as well...

  const size_t first_letter_index{ text.find_first_not_of(whitespace) };
  if (first_letter_index == std::string::npos)
  {
    // Is an empty string a tautogram? Let's not go there.
    return 0;
  }

  const char start_letter{ static_cast<char>(std::toupper(text[first_letter_index])) };
  bool tautogram{ true };

  for (size_t start_current_word{ first_letter_index };;)  // Use an indefinite loop (see the break; statements)
  {
    const size_t next_space_index{ text.find_first_of(whitespace, start_current_word) };
    if (next_space_index == std::string::npos)
    {
      break;
    }

    const size_t next_letter_index{ text.find_first_not_of(whitespace, next_space_index) };
    if (next_letter_index == std::string::npos)
    {
      break;
    }

    if (std::toupper(text[next_letter_index]) != start_letter)
    {
      tautogram = false;
      break;
    }

    start_current_word = next_letter_index;
  }
  
  std::cout << "The text that you entered is " << (tautogram ? "" : "not ") << "a tautogram.\n";
  if (tautogram)
  {
    std::cout << "All words start with the letter " << start_letter << ".\n";

    std::string text_without_start_letter;
    for (char c : text)
    {
      if (std::toupper(c) != start_letter)
      {
        text_without_start_letter.push_back(c);
      }
    }

    std::cout << "After removing this letter, the text becomes as follows:\n" << text_without_start_letter << std::endl;
  }
}