FizzBuzz あれこれ

fizzbuzz.cpp

#include <iostream>

#if 0

int main()
{
	for (int i = 1; i <= 100; ++i)
	{
		const int fizz = i % 3, buzz = i % 5;

		if (fizz == 0)
		{
			std::cout << "fizz";
		}

		if (buzz == 0)
		{
			std::cout << "buzz";
		}

		if (fizz && buzz)
		{
			std::cout << i;
		}

		std::cout << std::endl;
	}
}

#elif 0

struct fizzbuzz
{
	const int value;
};

std::ostream & operator<<(std::ostream & out, const fizzbuzz & obj)
{
	const int fizz = obj.value % 3, buzz = obj.value % 5;

	if (fizz == 0)
	{
		out << "fizz";
	}

	if (buzz == 0)
	{
		out << "buzz";
	}

	if (fizz && buzz)
	{
		out << obj.value;
	}

	return out;
}

fizzbuzz put_fizzbuzz(int i)
{
	return { i };
}

int main()
{
	for (int i = 1; i <= 100; ++i)
	{
		std::cout << put_fizzbuzz(i) << std::endl;
	}
}

#elif 0

class put_fizzbuzz
{
	const int value;

	friend std::ostream & operator<<(std::ostream & out, const put_fizzbuzz & obj)
	{
		const int fizz = obj.value % 3, buzz = obj.value % 5;

		if (fizz == 0)
		{
			out << "fizz";
		}

		if (buzz == 0)
		{
			out << "buzz";
		}

		if (fizz && buzz)
		{
			out << obj.value;
		}

		return out;
	}

public:
	put_fizzbuzz(int i) : value(i)
	{}
};

int main()
{
	for (int i = 1; i <= 100; ++i)
	{
		std::cout << put_fizzbuzz(i) << std::endl;
	}
}

#else

#include <variant>
#include <ranges>

using fizzbuzz = std::variant<const char *, int>;

fizzbuzz put_fizzbuzz(int i)
{
	const int fizz = i % 3, buzz = i % 5;

	if (fizz == 0 && buzz == 0)
	{
		return "fizzbuzz";
	}

	if (fizz == 0)
	{
		return "fizz";
	}

	if (buzz == 0)
	{
		return "buzz";
	}

	return i;
}

std::ostream & operator<<(std::ostream & out, const fizzbuzz & obj)
{
	if (auto p = std::get_if<const char *>(&obj); p != nullptr)
	{
		return out << *p;
	}

	return out << std::get<int>(obj);
}

int main()
{
	for (int i : std::ranges::views::iota(1, 100 + 1))
	{
		std::cout << put_fizzbuzz(i) << std::endl;
	}
}

#endif