对于这个用例，如果您预先知道每个线程产生的结果的数量，那么您可以预先分配AB并将std::span传递给每个线程。这样就不需要进行连接。例子:

std::vector<int> AB(total_number_of_results, 0);
std::size_t chunk_length = …;
std::size_t chunk2_start = chunk_length;
std::size_t chunk3_start = 2 * chunk_length; // If needed
…
// Pass these to the worker threads.
std::span<int> A(AB.data(), chunk_length);
std::span<int> B(AB.data() + chunk2_start, chunk_length);
…

AB.reserve( A.size() + B.size() ); // preallocate memory
AB.insert( AB.end(), A.begin(), A.end() );
AB.insert( AB.end(), B.begin(), B.end() );

基于Kiril V. Lyadvinsky的回答，我做了一个新的版本。这个片段使用模板和重载。有了它，你可以写vector3 = vector1 + vector2和vector4 += vector3。希望能有所帮助。

template <typename T>
std::vector<T> operator+(const std::vector<T> &A, const std::vector<T> &B)
{
    std::vector<T> AB;
    AB.reserve(A.size() + B.size());                // preallocate memory
    AB.insert(AB.end(), A.begin(), A.end());        // add A;
    AB.insert(AB.end(), B.begin(), B.end());        // add B;
    return AB;
}

template <typename T>
std::vector<T> &operator+=(std::vector<T> &A, const std::vector<T> &B)
{
    A.reserve(A.size() + B.size());                // preallocate memory without erase original data
    A.insert(A.end(), B.begin(), B.end());         // add B;
    return A;                                        // here A could be named AB
}

所有的解决方案都是正确的，但我发现写一个函数来实现它更容易。是这样的:

template <class T1, class T2>
void ContainerInsert(T1 t1, T2 t2)
{
    t1->insert(t1->end(), t2->begin(), t2->end());
}

这样你就可以避免像这样的临时放置:

ContainerInsert(vec, GetSomeVector());

我的回答是基于罗纳德·索萨先生最初的解决方案。除了他最初的解决方案，我还写了一个支持迭代器的向量代理!

对于那些不知道原始解决方案上下文的人来说，简短的描述:joined_vector模板类(即向量代理)将两个向量的两个引用作为构造函数参数，然后将它们视为一个连续的向量。我的实现还支持前向迭代器。

用法:

int main()
{
    std::vector<int> a1;
    std::vector<int> a2;

    joined_vector<std::vector<int>> jv(a1,a2);

    for (int i = 0; i < 5; i++)
        a1.push_back(i);
    for (int i = 5; i <=10; i++)
        a2.push_back(i);

    for (auto e : jv)
        std::cout << e<<"\n";
    for (int i = 0; i < jv.size(); i++)
        std::cout << jv[i] << "\n";
    return 0;
}

实现:

template<typename _vec>
class joined_vector
{
    _vec& m_vec1;
    _vec& m_vec2;

public:

    struct Iterator
    {
        typedef typename _vec::iterator::value_type type_value;
        typedef typename _vec::iterator::value_type* pointer;
        typedef typename _vec::iterator::value_type& reference;
        typedef std::forward_iterator_tag iterator_category;
        typedef std::ptrdiff_t difference_type;
        _vec* m_vec1;
        _vec* m_vec2;
        Iterator(pointer ptr) :m_ptr(ptr)
        {

        }
        Iterator operator++()
        {
            if (m_vec1->size() > 0 && m_ptr == &(*m_vec1)[m_vec1->size() - 1] && m_vec2->size() != 0)
                m_ptr = &(*m_vec2)[0];
            else
                ++m_ptr;
            return m_ptr;
        }
        Iterator operator++(int)
        {
            pointer curr = m_ptr;
            if (m_vec1->size() > 0 && m_ptr == &(*m_vec1)[m_vec1->size() - 1] && m_vec2->size() != 0)
                m_ptr = &(*m_vec2)[0];
            else
                ++m_ptr;
            return curr;
        }
        reference operator *()
        {
            return *m_ptr;
        }
        pointer operator ->()
        {
            return m_ptr;
        }

        friend bool operator == (Iterator& itr1, Iterator& itr2)
        {
            return itr1.m_ptr == itr2.m_ptr;
        }
        friend bool operator != (Iterator& itr1, Iterator& itr2)
        {
            return itr1.m_ptr != itr2.m_ptr;
        }
    private:
        pointer m_ptr;
    };

    joined_vector(_vec& vec1, _vec& vec2) :m_vec1(vec1), m_vec2(vec2)
    {

    }
    Iterator begin()
    {
        //checkes if m_vec1 is empty and gets the first elemet's address,
        //if it's empty then it get's the first address of the second vector m_vec2
        //if both of them are empty then nullptr is returned as the first pointer
        Iterator itr_beg((m_vec1.size() != 0) ? &m_vec1[0] : ((m_vec2.size() != 0) ? &m_vec2[0] : nullptr));
        itr_beg.m_vec1 = &m_vec1;
        itr_beg.m_vec2 = &m_vec2;
        return itr_beg;
    }
    Iterator end()
    {
        //check if m_vec2 is empty and get the last address of that vector
        //if the second vector is empty then the m_vec1's vector/the first vector's last element's address is taken
        //if both of them are empty then a null pointer is returned as the end pointer
        typename _vec::value_type* p = ((m_vec2.size() != 0) ? &m_vec2[m_vec2.size() - 1] : ((m_vec1.size()) != 0 ? &m_vec1[m_vec1.size() - 1] : nullptr));
        Iterator itr_beg(p != nullptr ? p + 1 : nullptr);
        itr_beg.m_vec1 = &m_vec1;
        itr_beg.m_vec2 = &m_vec2;
        return itr_beg;
    }
    typename _vec::value_type& operator [](int i)
    {
        if (i < m_vec1.size())
            return m_vec1[i];
        else
            return m_vec2[i - m_vec1.size()];
    }
    size_t size()
    {
        return m_vec1.size() + m_vec2.size();
    }

};

如果你的向量排序*，检查set_union从<algorithm>。

set_union(A.begin(), A.end(), B.begin(), B.end(), AB.begin());

链接中有一个更详细的例子。