#include <iostream>

int main()
{
    signed int s { -1 };
    unsigned int u { 1 };

    if (s < u)
        std::cout << "-1 is less than 1\n";
    else
        std::cout << "1 is less than -1\n";
}

#include <iostream>

int main() {
	constexpr size_t NoElem {10};

	const int arr[NoElem] {1,2,3,4,5,6,7,8,9,10};

	for (size_t i = NoElem - 1; i >= 0; --i)
		std::cout << arr[i] << ' ';

	std::cout << '\n';
}

#include <iostream>

int main() {
	constexpr size_t NoElem {10};

	const int arr[NoElem] {1,2,3,4,5,6,7,8,9,10};

	for (size_t i = NoElem; i > 0; --i)
		std::cout << arr[i - 1] << ' ';

	std::cout << '\n';
}

#include <iostream>

int main()
{
   constexpr size_t numElems { 10 };

   const int arr[numElems]   { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

   for (size_t i { numElems }; i-- > 0;)
   {
      std::cout << arr[i] << ' ';
   }

   std::cout << '\n';
}

#include <ranges>
#include <iostream>
 
int main()
{
    static constexpr auto il = {3, 1, 4, 1, 5, 9};
 
    std::ranges::reverse_view rv {il};
    for (int i : rv)
        std::cout << i << ' ';
    std::cout << '\n';
 
    for (int i : il | std::views::reverse)
        std::cout << i << ' ';
    std::cout << '\n';
 
    // operator[] is inherited from `view_interface`
    for (auto i{0U}; i != rv.size(); ++i)
        std::cout << rv[i] << ' ';
    std::cout << '\n';
}

#include <iostream>
#include <iterator>

template<typename InputIter>
class RangeF {
public:
	constexpr RangeF(const InputIter& b, const InputIter& e) : beg_(b), end_(e) {}

	constexpr auto begin() const noexcept { return beg_; }
	constexpr auto end() const noexcept { return end_; }

private:
	InputIter beg_ {};
	InputIter end_ {};
};

int main() {
	const int arr[] {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

	for (const auto a : RangeF(std::rbegin(arr), std::rend(arr)))
		std::cout << a << ' ';

	std::cout << '\n';
}

#include <iostream>
#include <iterator>

int main()
{
   constexpr size_t numElems { 10 };

   const int arr[numElems]   { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

   for (auto itr { std::rbegin(arr) }; itr != std::rend(arr); ++itr)
   {
      std::cout << *itr << ' ';
   }

   std::cout << '\n';
}

#include <ranges>
#include <iostream>
 
int main()
{
    static constexpr auto il = {3, 1, 4, 1, 5, 9};
 
    for (int i : il | std::views::reverse)
        std::cout << i << ' ';
    std::cout << '\n';
}