使用可变模板连接多个std::array对象

#include <array>

// 辅助函数，用于连接两个std::array对象
template<typename T, std::size_t N1, std::size_t N2, std::size_t... Indices1, std::size_t... Indices2>
constexpr std::array<T, N1 + N2> concatArraysHelper(const std::array<T, N1>& arr1, const std::array<T, N2>& arr2, std::index_sequence<Indices1...>, std::index_sequence<Indices2...>)
{
    return { arr1[Indices1]..., arr2[Indices2]... };
}

// 主函数，用于连接多个std::array对象
template<typename T, std::size_t N, typename... Arrays>
constexpr std::array<T, N> concatArrays(const std::array<T, N>& arr, const Arrays&... arrays)
{
    if constexpr (sizeof...(arrays) == 0)
    {
        return arr;
    }
    else
    {
        constexpr std::size_t totalSize = (N + arrays.size())...;
        std::array<T, totalSize> result;
        std::size_t currentIndex = 0;
        auto helper = [&](const auto& currentArray)
        {
            for (const auto& element : currentArray)
            {
                result[currentIndex++] = element;
            }
        };
        helper(arr);
        (helper(arrays), ...);
        return result;
    }
}

#include <iostream>

int main()
{
    std::array<int, 3> arr1 = { 1, 2, 3 };
    std::array<int, 2> arr2 = { 4, 5 };
    std::array<int, 4> arr3 = { 6, 7, 8, 9 };

    auto result = concatArrays(arr1, arr2, arr3);

    for (const auto& element : result)
    {
        std::cout << element << " ";
    }
    std::cout << std::endl;

    return 0;
}