Question

为了理解priority_queue，我编写了以下C ++程序。

#include <queue>

struct Node {                                                                                                                                                  
    bool operator<(const Node& r) {                                                                                                                            
        return a < r.a;                                                                                                                                        
    }                                                                                                                                                          

    int a;                                                                                                                                                     
};

int main(int argc, char *argv[])                                                                                                                               
{                                                                                                                                                              
    std::priority_queue<Node, std::vector<Node>> heap;                                                                                                         
    return 0;                                                                                                                                                  
}

我正在使用以下命令编译它。

g++ -c testMinHeap.cpp -std=c++1y

但是它导致了以下错误。

g++ -c testMinHeap.cpp -g -std=c++1y
In file included from /usr/include/c++/5/queue:63:0,
                 from testMinHeap.cpp:1:
/usr/include/c++/5/bits/stl_function.h: In instantiation of ‘constexpr bool std::less<_Tp>::operator()(const _Tp&, const _Tp&) const [with _Tp = Node]’:
/usr/include/c++/5/bits/predefined_ops.h:123:46:   required from ‘constexpr bool __gnu_cxx::__ops::_Iter_comp_iter<_Compare>::operator()(_Iterator1, _Iterator\
2) [with _Iterator1 = __gnu_cxx::__normal_iterator<Node*, std::vector<Node> >; _Iterator2 = __gnu_cxx::__normal_iterator<Node*, std::vector<Node> >; _Compare \
= std::less<Node>]’
/usr/include/c++/5/bits/stl_heap.h:215:14:   required from ‘void std::__adjust_heap(_RandomAccessIterator, _Distance, _Distance, _Tp, _Compare) [with _RandomA\
ccessIterator = __gnu_cxx::__normal_iterator<Node*, std::vector<Node> >; _Distance = long int; _Tp = Node; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<std::l\
ess<Node> >]’
/usr/include/c++/5/bits/stl_heap.h:333:22:   required from ‘void std::__make_heap(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessI\
terator = __gnu_cxx::__normal_iterator<Node*, std::vector<Node> >; _Compare = __gnu_cxx::__ops::_Iter_comp_iter<std::less<Node> >]’
/usr/include/c++/5/bits/stl_heap.h:384:23:   required from ‘void std::make_heap(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIte\
rator = __gnu_cxx::__normal_iterator<Node*, std::vector<Node> >; _Compare = std::less<Node>]’
/usr/include/c++/5/bits/stl_queue.h:414:23:   required from ‘std::priority_queue<_Tp, _Sequence, _Compare>::priority_queue(const _Compare&, _Sequence&&) [with\
 _Tp = Node; _Sequence = std::vector<Node>; _Compare = std::less<Node>]’
testMinHeap.cpp:13:47:   required from here
/usr/include/c++/5/bits/stl_function.h:387:20: error: no match for ‘operator<’ (operand types are ‘const Node’ and ‘const Node’)
       { return __x < __y; }
                    ^
testMinHeap.cpp:4:7: note: candidate: bool Node::operator<(const Node&) <near match>
  bool operator<(const Node& r) {
       ^

没有得到＆＃39;＆lt;＆＃39;（小于）运算符的定义。在priority_queue变量声明期间，我没有给出 Comp 模板参数，假设它将使用 less＆lt; T＆gt; 是默认值。对于类型T（即节点），我已经重载了运算符＆lt; 。如果我在这里做错了，请指出我。

感谢。

c ++中的priority_queue模板实例化

0 个答案: