如何将队列元素插入到矢量中？

Question

我有

typedef std::queue<MyObject*> InputQueue;
std::vector<InputQueue> inp_queue;

现在我要做的是在运行时定义5个队列，并将数据放在这些队列上，如

inp_queue[1].push(new MyObject());

等

我让它编译，但它立即核心转储。我想我需要首先将队列添加到向量中（它们不会像地图一样自动创建）。如何在没有队列指针的情况下添加队列？

编辑：

我应该指出我正在使用的队列类不是std :: queue，而是这个：http://www.justsoftwaresolutions.co.uk/threading/implementing-a-thread-safe-queue-using-condition-variables.html

我没想到编译器会抱怨它，否则我会事先说出来。

不幸的是，当我编译应用程序时，我得到了这个编译错误。

g++ test.cpp
In file included from /usr/include/c++/4.4/deque:63,
                 from /usr/include/c++/4.4/queue:61,
                 from concurrentqueue.h:3,
                 from test.cpp:1:
/usr/include/c++/4.4/bits/stl_construct.h: In function ‘void std::_Construct(_T1*, const _T2&) [with _T1 = concurrent_queue<Packet*>, _T2 = concurrent_queue<Packet*>]’:
/usr/include/c++/4.4/bits/stl_uninitialized.h:187:   instantiated from ‘static void std::__uninitialized_fill_n<<anonymous> >::uninitialized_fill_n(_ForwardIterator, _Size, const _Tp&) [with _ForwardIterator = concurrent_queue<Packet*>*, _Size = long unsigned int, _Tp = concurrent_queue<Packet*>, bool <anonymous> = false]’
/usr/include/c++/4.4/bits/stl_uninitialized.h:223:   instantiated from ‘void std::uninitialized_fill_n(_ForwardIterator, _Size, const _Tp&) [with _ForwardIterator = concurrent_queue<Packet*>*, _Size = long unsigned int, _Tp = concurrent_queue<Packet*>]’
/usr/include/c++/4.4/bits/stl_uninitialized.h:318:   instantiated from ‘void std::__uninitialized_fill_n_a(_ForwardIterator, _Size, const _Tp&, std::allocator<_Tp2>&) [with _ForwardIterator = concurrent_queue<Packet*>*, _Size = long unsigned int, _Tp = concurrent_queue<Packet*>, _Tp2 = concurrent_queue<Packet*>]’
/usr/include/c++/4.4/bits/stl_vector.h:1035:   instantiated from ‘void std::vector<_Tp, _Alloc>::_M_fill_initialize(size_t, const _Tp&) [with _Tp = concurrent_queue<Packet*>, _Alloc = std::allocator<concurrent_queue<Packet*> >]’
/usr/include/c++/4.4/bits/stl_vector.h:230:   instantiated from ‘std::vector<_Tp, _Alloc>::vector(size_t, const _Tp&, const _Alloc&) [with _Tp = concurrent_queue<Packet*>, _Alloc = std::allocator<concurrent_queue<Packet*> >]’
test.cpp:18:   instantiated from here
/usr/include/c++/4.4/bits/stl_construct.h:74: error: no matching function for call to ‘concurrent_queue<Packet*>::concurrent_queue(const concurrent_queue<Packet*>&)’
concurrentqueue.h:12: note: candidates are: concurrent_queue<Packet*>::concurrent_queue()
concurrentqueue.h:12: note:                 concurrent_queue<Packet*>::concurrent_queue(concurrent_queue<Packet*>&)

Answer 1

您尚未分配5个队列中的任何一个。尝试：

typedef std::queue<MyObject*> InputQueue;
std::vector<InputQueue> inp_queue(5);
inp_queue[1].push(new MyObject());

同样不是std::vector使用从0开始的索引，所以要插入第一个队列：

inp_queue[0].push(new MyObject());

编辑的后续行动：并发队列似乎没有复制构造函数。这意味着您无法将其放在任何标准容器中，因为它不满足要求。容器的value-type必须是可复制构造和可复制的。

Answer 2

您必须为五个队列分配内存：

for (size_t queue_num=0;queue_num<5;++queue_num)
  inp_queue.push_back(InputQueue());

或

inp_queue.resize(5,InputQueue());

现在，你可以这样做：

inp_queue[1].push_back(new MyObject);