chapter7ex8.cpp

// Osman Zakir
// 12 / 12 / 2021
// Beginning C++20: From Novice to Professional by Ivor Horton and Peter Van Weert
// Chapter 7 Exercise 8
// Exercise Specs:
/**
 * A tautogram is a body of text in which all words start with the same letter. In
 * English, an example would be “truly tautograms triumph, trumpeting trills to trounce terrible
 * travesties.” Ask the user for a string, and verify whether it is a tautogram (ignoring casing). If
 * it is, output also the letter by which each word starts.
 * 
 * Note: True tautograms are truly tough to throw together, so perhaps you can bend the rules
 * a bit? Maybe allow short words to glue the text together (such as “a,” “to,” “is,” “are,” etc.),
 * or only require a certain percentage of words to begin with the same letter? have some fun
 * with it!
 */

import <algorithm>;
import <iostream>;
import <string>;
import <vector>;
#include <cctype>

int main()
{
	std::string text;
	std::cout << "Enter a single sentence of text (you may add some words that don't begin with the same "
		      << "letter if it seems hard to make a true tautogram):\n";
	std::getline(std::cin, text);

	constexpr double tautogram_percentage_value{ 75.0 / 100.0 };
	const double tolerated_nontautogram_percent{ 15.0 / 100.0 };
	const std::string separators{ " .,:;!\"" };
	std::size_t start{ text.find_first_not_of(separators) };
	std::vector<std::string> words;
	while (start != std::string::npos)
	{
		std::size_t end{ text.find_first_of(separators, start + 1) };
		if (end == std::string::npos)
		{
			end = text.length();
		}
		words.push_back(text.substr(start, end - start));
		start = text.find_first_not_of(separators, end + 1);
	}

	// take out any single quotes
	using namespace std::string_literals;
	for (auto& word : words)
	{
		if (word.starts_with('\'') && word.ends_with('\''))
		{
			word.erase(0, 1);
			word.erase(word.length() - 1, 1);
		}
		if (word.starts_with('\''))
		{
			word.erase(0, 1);
		}
		if (word.ends_with('\''))
		{
			word.erase(word.length() - 1);
		}
	}

	std::for_each(words.begin(), words.end(),
		[](auto& word)
		{
			for (auto& ch : word)
			{
				ch = std::tolower(ch);
			}
		});
	unsigned num_taut{};   // to hold number of letters starting with same letter
	                       // (number of tautogram words)
	const char first_letter{ words[0][0] };
	for (const auto& word : words)
	{
		if (word.starts_with(std::tolower(first_letter)))
		{
			num_taut++;
		}
	}

	if (num_taut == words.size())
	{
		std::cout << "Your sentence is a true tautogram!\nThe letter all words start with "
			      << "is " << first_letter << ".\n";
	}
	else if (num_taut < words.size())
	{
		if (num_taut / words.size() >= tautogram_percentage_value)
		{
			std::cout << "Your sentence is at least 75% tautogram, so we'll say it is one.\n"
				      << "The letter all words start with is " << first_letter << ".\n";
		}
		else if (num_taut / words.size() < tautogram_percentage_value)
		{
			std::cout << "Your sentence is not a tautogram.\n";
		}
	}
}