std::tuple遍历

遇到个需要将两个std::tuple对应元素分别求平均值的需求
实现

#include <iostream>
#include <tuple>

template <typename T, size_t S = 0, size_t E = std::tuple_size<T>::value>
void _avg(const T &t1, const T &t2, T &rs)
{
    std::get<E - 1>(rs) = (std::get<E - 1>(t1) + std::get<E - 1>(t2)) / 2;
    if constexpr (E - 1 > S && E - 1 > 0)
    {
        _avg<T, S, E - 1>(t1, t2, rs);
    }
}

template <typename T, size_t S = 0, size_t E = std::tuple_size<T>::value>
T avg(const T &t1, const T &t2)
{
    T rs;
    _avg<T, S, E>(t1, t2, rs);
    return rs;
}

// 遍历输出 tuple
template <typename T, int N, size_t S = 0, size_t E = std::tuple_size<T>::value>
void _print(const T &t)
{
    std::cout << std::get<N - 1>(t) << '\t';
    if constexpr (N - 1 > S && N - 1 < E)
    {
        _print<T, N - 1, S, E>(t);
    }
}

template <typename T, int N = std::tuple_size<T>::value, size_t S = 0, size_t E = std::tuple_size<T>::value>
void print(const T &t)
{
    _print<T, N, S, E>(t);
}

int main()
{
    auto t1 = std::make_tuple(2, 4, 6, 8, 10, 12, 14, 16, 18, 20);
    auto t2 = std::make_tuple(4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048);
    auto rs = avg<decltype(t1)>(t1, t2);

    print<decltype(rs), std::tuple_size<decltype(rs)>::value>(rs);
    return 0;
}