Compile time #3 itoa (number to string)

• Time : $O(log_{X}(Base))$
• Space : $O(log_{X}(Base))$

c++

using namespace std;
constexpr char ord[] = "0123456789abcdefghijklmnopqrstuvwxyz";
using integer = unsigned long long;
template <integer X, integer Base = 10>
struct itoax {
    static constexpr size_t digits() {
        if (X == 0) return 1;
        auto q = X;
        size_t size = 0;
        while (q > 0) {
            q /= Base;
            size++;
        }
        return size;
    }
    static constexpr auto value_array = []() constexpr {
        std::array<char, digits() + 1> a{};
        if (X == 0) {
            a[0] = '0';
            a[1] = '\0';
        }
        else {
            auto q = X;
            auto index = digits() - 1;
            a[index] = '\0';
            while (q > 0) {
                a[index--] = ord[q % Base];
                q /= Base;
            }
        }
        return a;
    }();
    static constexpr const char* value = value_array.data();
};