How to add struct, vector of struct to map within class

Question

My issue is in the following .h:

#include <iostream>
#include <map>
#include <vector>

struct Node {
    int data;
};

class Graph {

std::map< Node, std::vector<Node> > edge_map;

public:
    Graph();

    void add_neighbor(Node cur_node, Node new_node);

    void remove_neighbor(Node cur_node, Node del_node);

    virtual ~Graph();
};

and in trying to implement the add_neighbor function, but I'm fumbling through the details and need some direction. What I've got so far (not functional) is the following:

void Graph::add_neighbor(Node cur_node, Node new_node) {
    if (edge_map.find(cur_node) == edge_map.end()) {
        edge_map.insert(std::pair<Node, std::vector<Node> >(cur_node, std::vector<Node>()));
        edge_map[cur_node].push_back(new_node);
    }
    else {
        edge_map[cur_node].push_back(new_node);
    }
}

I can copy the explosion that g++ -std=c++11 throws at me, but it's not very helpful. How can I include a map as a class member where the key, value are struct, vector of struct, and then have a function in the .cpp that can add it? I'll also need the remove function, but once I understand how to treat the data in the insertion function I'll know what I need, I think.

EDIT (including the compiler vomit):

In file included from /usr/include/c++/4.8/string:48:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from graph.cpp:1:
/usr/include/c++/4.8/bits/stl_function.h: In instantiation of ‘bool std::less<_Tp>::operator()(const _Tp&, const _Tp&) const [with _Tp = Node]’:
/usr/include/c++/4.8/bits/stl_map.h:463:31:   required from ‘std::map<_Key, _Tp, _Compare, _Alloc>::mapped_type& std::map<_Key, _Tp, _Compare, _Alloc>::operator[](const key_type&) [with _Key = Node; _Tp = std::vector<Node>; _Compare = std::less<Node>; _Alloc = std::allocator<std::pair<const Node, std::vector<Node> > >; std::map<_Key, _Tp, _Compare, _Alloc>::mapped_type = std::vector<Node>; std::map<_Key, _Tp, _Compare, _Alloc>::key_type = Node]’
graph.cpp:14:26:   required from here
/usr/include/c++/4.8/bits/stl_function.h:235:20: error: no match for ‘operator<’ (operand types are ‘const Node’ and ‘const Node’)
       { return __x < __y; }
                    ^
/usr/include/c++/4.8/bits/stl_function.h:235:20: note: candidates are:
In file included from /usr/include/c++/4.8/bits/stl_algobase.h:64:0,
                 from /usr/include/c++/4.8/bits/char_traits.h:39,
                 from /usr/include/c++/4.8/ios:40,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from graph.cpp:1:
/usr/include/c++/4.8/bits/stl_pair.h:220:5: note: template<class _T1, class _T2> constexpr bool std::operator<(const std::pair<_T1, _T2>&, const std::pair<_T1, _T2>&)
     operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
     ^
/usr/include/c++/4.8/bits/stl_pair.h:220:5: note:   template argument deduction/substitution failed:
In file included from /usr/include/c++/4.8/string:48:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from graph.cpp:1:
/usr/include/c++/4.8/bits/stl_function.h:235:20: note:   ‘const Node’ is not derived from ‘const std::pair<_T1, _T2>’
       { return __x < __y; }
                    ^
In file included from /usr/include/c++/4.8/bits/stl_algobase.h:67:0,
                 from /usr/include/c++/4.8/bits/char_traits.h:39,
                 from /usr/include/c++/4.8/ios:40,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from graph.cpp:1:
/usr/include/c++/4.8/bits/stl_iterator.h:297:5: note: template<class _Iterator> bool std::operator<(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_Iterator>&)
     operator<(const reverse_iterator<_Iterator>& __x,
     ^
/usr/include/c++/4.8/bits/stl_iterator.h:297:5: note:   template argument deduction/substitution failed:
In file included from /usr/include/c++/4.8/string:48:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from graph.cpp:1:
/usr/include/c++/4.8/bits/stl_function.h:235:20: note:   ‘const Node’ is not derived from ‘const std::reverse_iterator<_Iterator>’
       { return __x < __y; }
                    ^
In file included from /usr/include/c++/4.8/bits/stl_algobase.h:67:0,
                 from /usr/include/c++/4.8/bits/char_traits.h:39,
                 from /usr/include/c++/4.8/ios:40,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from graph.cpp:1:
/usr/include/c++/4.8/bits/stl_iterator.h:347:5: note: template<class _IteratorL, class _IteratorR> bool std::operator<(const std::reverse_iterator<_Iterator>&, const std::reverse_iterator<_IteratorR>&)
     operator<(const reverse_iterator<_IteratorL>& __x,
     ^
/usr/include/c++/4.8/bits/stl_iterator.h:347:5: note:   template argument deduction/substitution failed:
In file included from /usr/include/c++/4.8/string:48:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from graph.cpp:1:
/usr/include/c++/4.8/bits/stl_function.h:235:20: note:   ‘const Node’ is not derived from ‘const std::reverse_iterator<_Iterator>’
       { return __x < __y; }
                    ^
In file included from /usr/include/c++/4.8/bits/stl_algobase.h:67:0,
                 from /usr/include/c++/4.8/bits/char_traits.h:39,
                 from /usr/include/c++/4.8/ios:40,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from graph.cpp:1:
/usr/include/c++/4.8/bits/stl_iterator.h:1055:5: note: template<class _IteratorL, class _IteratorR> bool std::operator<(const std::move_iterator<_Iterator>&, const std::move_iterator<_IteratorR>&)
     operator<(const move_iterator<_IteratorL>& __x,
     ^
/usr/include/c++/4.8/bits/stl_iterator.h:1055:5: note:   template argument deduction/substitution failed:
In file included from /usr/include/c++/4.8/string:48:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from graph.cpp:1:
/usr/include/c++/4.8/bits/stl_function.h:235:20: note:   ‘const Node’ is not derived from ‘const std::move_iterator<_Iterator>’
       { return __x < __y; }
                    ^
In file included from /usr/include/c++/4.8/bits/stl_algobase.h:67:0,
                 from /usr/include/c++/4.8/bits/char_traits.h:39,
                 from /usr/include/c++/4.8/ios:40,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from graph.cpp:1:
/usr/include/c++/4.8/bits/stl_iterator.h:1061:5: note: template<class _Iterator> bool std::operator<(const std::move_iterator<_Iterator>&, const std::move_iterator<_Iterator>&)
     operator<(const move_iterator<_Iterator>& __x,
     ^
/usr/include/c++/4.8/bits/stl_iterator.h:1061:5: note:   template argument deduction/substitution failed:
In file included from /usr/include/c++/4.8/string:48:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from graph.cpp:1:
/usr/include/c++/4.8/bits/stl_function.h:235:20: note:   ‘const Node’ is not derived from ‘const std::move_iterator<_Iterator>’
       { return __x < __y; }
                    ^
In file included from /usr/include/c++/4.8/string:52:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from graph.cpp:1:
/usr/include/c++/4.8/bits/basic_string.h:2569:5: note: template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const std::basic_string<_CharT, _Traits, _Alloc>&, const std::basic_string<_CharT, _Traits, _Alloc>&)
     operator<(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
     ^
/usr/include/c++/4.8/bits/basic_string.h:2569:5: note:   template argument deduction/substitution failed:
In file included from /usr/include/c++/4.8/string:48:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from graph.cpp:1:
/usr/include/c++/4.8/bits/stl_function.h:235:20: note:   ‘const Node’ is not derived from ‘const std::basic_string<_CharT, _Traits, _Alloc>’
       { return __x < __y; }
                    ^
In file included from /usr/include/c++/4.8/string:52:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from graph.cpp:1:
/usr/include/c++/4.8/bits/basic_string.h:2581:5: note: template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const std::basic_string<_CharT, _Traits, _Alloc>&, const _CharT*)
     operator<(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
     ^
/usr/include/c++/4.8/bits/basic_string.h:2581:5: note:   template argument deduction/substitution failed:
In file included from /usr/include/c++/4.8/string:48:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from graph.cpp:1:
/usr/include/c++/4.8/bits/stl_function.h:235:20: note:   ‘const Node’ is not derived from ‘const std::basic_string<_CharT, _Traits, _Alloc>’
       { return __x < __y; }
                    ^
In file included from /usr/include/c++/4.8/string:52:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from graph.cpp:1:
/usr/include/c++/4.8/bits/basic_string.h:2593:5: note: template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const _CharT*, const std::basic_string<_CharT, _Traits, _Alloc>&)
     operator<(const _CharT* __lhs,
     ^
/usr/include/c++/4.8/bits/basic_string.h:2593:5: note:   template argument deduction/substitution failed:
In file included from /usr/include/c++/4.8/string:48:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from graph.cpp:1:
/usr/include/c++/4.8/bits/stl_function.h:235:20: note:   mismatched types ‘const _CharT*’ and ‘Node’
       { return __x < __y; }
                    ^
In file included from /usr/include/c++/4.8/vector:64:0,
                 from graph.cpp:2:
/usr/include/c++/4.8/bits/stl_vector.h:1421:5: note: template<class _Tp, class _Alloc> bool std::operator<(const std::vector<_Tp, _Alloc>&, const std::vector<_Tp, _Alloc>&)
     operator<(const vector<_Tp, _Alloc>& __x, const vector<_Tp, _Alloc>& __y)
     ^
/usr/include/c++/4.8/bits/stl_vector.h:1421:5: note:   template argument deduction/substitution failed:
In file included from /usr/include/c++/4.8/string:48:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from graph.cpp:1:
/usr/include/c++/4.8/bits/stl_function.h:235:20: note:   ‘const Node’ is not derived from ‘const std::vector<_Tp, _Alloc>’
       { return __x < __y; }
                    ^
In file included from /usr/include/c++/4.8/tuple:39:0,
                 from /usr/include/c++/4.8/functional:55,
                 from /usr/include/c++/4.8/bits/stl_algo.h:66,
                 from /usr/include/c++/4.8/algorithm:62,
                 from graph.cpp:3:
/usr/include/c++/4.8/array:238:5: note: template<class _Tp, long unsigned int _Nm> bool std::operator<(const std::array<_Tp, _Nm>&, const std::array<_Tp, _Nm>&)
     operator<(const array<_Tp, _Nm>& __a, const array<_Tp, _Nm>& __b)
     ^
/usr/include/c++/4.8/array:238:5: note:   template argument deduction/substitution failed:
In file included from /usr/include/c++/4.8/string:48:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from graph.cpp:1:
/usr/include/c++/4.8/bits/stl_function.h:235:20: note:   ‘const Node’ is not derived from ‘const std::array<_Tp, _Nm>’
       { return __x < __y; }
                    ^
In file included from /usr/include/c++/4.8/functional:55:0,
                 from /usr/include/c++/4.8/bits/stl_algo.h:66,
                 from /usr/include/c++/4.8/algorithm:62,
                 from graph.cpp:3:
/usr/include/c++/4.8/tuple:824:5: note: template<class ... _TElements, class ... _UElements> constexpr bool std::operator<(const std::tuple<_Elements ...>&, const std::tuple<_Elements ...>&)
     operator<(const tuple<_TElements...>& __t,
     ^
/usr/include/c++/4.8/tuple:824:5: note:   template argument deduction/substitution failed:
In file included from /usr/include/c++/4.8/string:48:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from graph.cpp:1:
/usr/include/c++/4.8/bits/stl_function.h:235:20: note:   ‘const Node’ is not derived from ‘const std::tuple<_Elements ...>’
       { return __x < __y; }
                    ^
In file included from /usr/include/c++/4.8/map:60:0,
                 from graph.h:2,
                 from graph.cpp:4:
/usr/include/c++/4.8/bits/stl_tree.h:917:5: note: template<class _Key, class _Val, class _KeyOfValue, class _Compare, class _Alloc> bool std::operator<(const std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>&, const std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>&)
     operator<(const _Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>& __x,
     ^
/usr/include/c++/4.8/bits/stl_tree.h:917:5: note:   template argument deduction/substitution failed:
In file included from /usr/include/c++/4.8/string:48:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from graph.cpp:1:
/usr/include/c++/4.8/bits/stl_function.h:235:20: note:   ‘const Node’ is not derived from ‘const std::_Rb_tree<_Key, _Val, _KeyOfValue, _Compare, _Alloc>’
       { return __x < __y; }
                    ^
In file included from /usr/include/c++/4.8/map:61:0,
                 from graph.h:2,
                 from graph.cpp:4:
/usr/include/c++/4.8/bits/stl_map.h:979:5: note: template<class _Key, class _Tp, class _Compare, class _Alloc> bool std::operator<(const std::map<_Key, _Tp, _Compare, _Alloc>&, const std::map<_Key, _Tp, _Compare, _Alloc>&)
     operator<(const map<_Key, _Tp, _Compare, _Alloc>& __x,
     ^
/usr/include/c++/4.8/bits/stl_map.h:979:5: note:   template argument deduction/substitution failed:
In file included from /usr/include/c++/4.8/string:48:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from graph.cpp:1:
/usr/include/c++/4.8/bits/stl_function.h:235:20: note:   ‘const Node’ is not derived from ‘const std::map<_Key, _Tp, _Compare, _Alloc>’
       { return __x < __y; }
                    ^
In file included from /usr/include/c++/4.8/map:62:0,
                 from graph.h:2,
                 from graph.cpp:4:
/usr/include/c++/4.8/bits/stl_multimap.h:881:5: note: template<class _Key, class _Tp, class _Compare, class _Alloc> bool std::operator<(const std::multimap<_Key, _Tp, _Compare, _Alloc>&, const std::multimap<_Key, _Tp, _Compare, _Alloc>&)
     operator<(const multimap<_Key, _Tp, _Compare, _Alloc>& __x,
     ^
/usr/include/c++/4.8/bits/stl_multimap.h:881:5: note:   template argument deduction/substitution failed:
In file included from /usr/include/c++/4.8/string:48:0,
                 from /usr/include/c++/4.8/bits/locale_classes.h:40,
                 from /usr/include/c++/4.8/bits/ios_base.h:41,
                 from /usr/include/c++/4.8/ios:42,
                 from /usr/include/c++/4.8/ostream:38,
                 from /usr/include/c++/4.8/iostream:39,
                 from graph.cpp:1:
/usr/include/c++/4.8/bits/stl_function.h:235:20: note:   ‘const Node’ is not derived from ‘const std::multimap<_Key, _Tp, _Compare, _Alloc>’
       { return __x < __y; }
                    ^

Answer 1

In order for std::map to order it's entrys, it requires an operator<.

In your case, it can be as simple as this:

bool operator<(const Node & left, const Node & right)
{
  return left.data < right.data;
}