mhepeyiler

#include <iostream>
#include <type_traits>
int main()
{
    int x = 0;
    int &rx = x;
    int &&rri = 10;
    std::cout << std::boolalpha;
    std::cout << std::is_lvalue_reference_v<decltype(rx)> << '\n'; // true
    std::cout << std::is_rvalue_reference_v<decltype(rx)> << '\n'; // false

mhepeyiler

template<unsigned long long n>
constexpr unsigned long long Factorial = n * Factorial<n - 1>;

template<>
constexpr unsigned long long Factorial<0> = 1;

int main()
{
	constexpr auto fact_5 = Factorial<5>;   // 120
	constexpr auto fact_7 = Factorial<7>;   // 5040