Question

我有一个用户定义的类，它应该是unsorted_map的值类型。我的问题是，插入不起作用（使用gcc 4.7编译时已经是一个静态错误）。

我的班级：

class bk_tree {

public:
    bk_point *root;
    DISTANCE_FUN metric;
    int max_depth;

    //assume words not empty
    bk_tree() {metric=NULL; root=NULL; max_depth = 0;}

    //rule of three
    bk_tree(const bk_tree& copy_this) {metric=copy_this.metric; root=copy_this.root; max_depth = copy_this.max_depth;}
    bk_tree& operator=(const bk_tree& copy_this) { metric=copy_this.metric; root=copy_this.root; max_depth = copy_this.max_depth; return *this; }
    ~bk_tree() { delete root; }

    bk_tree(unordered_set<string> *words, DISTANCE_FUN _metric);
    bk_tree(DISTANCE_FUN _metric) { metric = _metric; root = NULL; max_depth = 0;        
};

代码以创建地图并插入：

 #include<tr/unordered_map>
 using namespace std;
 using namespace std::tr1;

 unordered_map<DocID, sigmod::bk_tree> *my_map = new unordered_map<DocID, sigmod::bk_tree>;
 sigmod::bk_tree my_value = sigmod::bk_tree(&words, sigmod::hamming_distance_metric);
 doc_bk_hamming->insert(make_pair(my_key, my_value));

编译（g ++ -O3 -std = c ++ 11 -fopenmp -fPIC -Wall -g -I.-I./include -c -o ref_impl / core.o）错误：

ref_impl/core.cpp
In file included from /usr/include/c++/4.7/bits/move.h:57:0,
                 from /usr/include/c++/4.7/bits/stl_pair.h:61,
                 from /usr/include/c++/4.7/bits/stl_algobase.h:65,
                 from /usr/include/c++/4.7/bits/char_traits.h:41,
                 from /usr/include/c++/4.7/string:42,
                 from ref_impl/../include/metric.h:5,
                 from ref_impl/core.cpp:29:
/usr/include/c++/4.7/type_traits: In instantiation of ‘struct std::is_convertible<const std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false>&, std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false> >’:
/usr/include/c++/4.7/type_traits:116:12:   required from ‘struct std::__and_<std::is_convertible<const std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false>&, std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false> >, std::is_convertible<const bool&, bool> >’
/usr/include/c++/4.7/bits/stl_pair.h:113:38:   required from here
/usr/include/c++/4.7/type_traits:1263:12: error: the value of ‘std::__is_convertible_helper<const std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false>&, std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false>, false>::value’ is not usable in a constant expression
/usr/include/c++/4.7/type_traits:1258:70: note: ‘std::__is_convertible_helper<const std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false>&, std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false>, false>::value’ used in its own initializer
/usr/include/c++/4.7/type_traits:1263:12: note: in template argument for type ‘bool’ 
/usr/include/c++/4.7/type_traits: In instantiation of ‘struct std::__and_<std::is_convertible<const std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false>&, std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false> >, std::is_convertible<const bool&, bool> >’:
/usr/include/c++/4.7/bits/stl_pair.h:113:38:   required from here
/usr/include/c++/4.7/type_traits:116:12: error: ‘value’ is not a member of ‘std::is_convertible<const std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false>&, std::tr1::__detail::_Hashtable_iterator<std::pair<const unsigned int, sigmod::bk_tree>, false, false> >’

Answer 1

DocID类型是否可以播放？这对于unordered_map的密钥类型是必要的，这就是这个公司抱怨的内容。另一方面，DocID听起来像支持订单，为什么不使用地图，这是作为二叉搜索树实现的？

此外，您的复制构造函数和复制赋值运算符已损坏。他们复制指针，然后原始对象和副本都认为他们拥有资源。如果其中一个被破坏，资源将被删除，导致另一个对象被破坏时双重释放。

Answer 2

有很多遗漏的信息阻止我们给你一个正确的答案。例如，doc_bk_hamming是什么？您分配并unordered_map并将其地址分配给指针my_map。但是，您要将(my_key, my_value)对插入我们未看到的doc_bk_hamming指向的地图中。

Unordered_map：自己的值类型问题

2 个答案: