C++ Vector of classes push back error

Question

I'm new in C++ , i use G++ compiler (Ubuntu 4.8.1-2ubuntu1~12.04) 4.8.1
i try to implement undirected wieghted Graph. by two classes Edges and Graph. but the compiler gives me this error

the compiler gives this error

/usr/include/c++/4.8/ext/new_allocator.h: In instantiation of 'void __gnu_cxx::new_allocator<_Tp>::construct(_Up*, _Args&& ...) [with _Up = UNDIR_W_EDGE; _Args = {const UNDIR_W_EDGE&}; _Tp = UNDIR_W_EDGE]': /usr/include/c++/4.8/bits/alloc_traits.h:254:4: required from 'static typename std::enable_ifAlloc>::_construct_helper<_Tp, _Args>::value, void>::type std::allocator_traits<_Alloc>::_S_construct(_Alloc&, _Tp*, _Args&& ...) [with _Tp = UNDIR_W_EDGE; _Args = {const UNDIR_W_EDGE&}; _Alloc = std::allocator; typename std::enable_ifAlloc>::_construct_helper<_Tp, _Args>::value, void>::type = void]' /usr/include/c++/4.8/bits/alloc_traits.h:393:57: required from 'static decltype (_S_construct(__a, __p, (forward<_Args>)(std::allocator_traits::construct::__args)...)) std::allocator_traits<_Alloc>::construct(_Alloc&, _Tp*, _Args&& ...) [with _Tp = UNDIR_W_EDGE; _Args = {const UNDIR_W_EDGE&}; _Alloc = std::allocator; decltype (_S_construct(__a, __p, (forward<_Args>)(std::allocator_traits::construct::__args)...)) = ]' /usr/include/c++/4.8/bits/stl_vector.h:906:34: required from 'void std::vector<_Tp, _Alloc>::push_back(const value_type&) [with _Tp = UNDIR_W_EDGE; _Alloc = std::allocator; std::vector<_Tp, _Alloc>::value_type = UNDIR_W_EDGE]' ../src/GRAPH.h:31:5: required from 'void GRAPH::addEdge(const Edge&) [with Edge = UNDIR_W_EDGE]' ../src/main.cpp:32:13: required from here /usr/include/c++/4.8/ext/new_allocator.h:120:4: error: no matching function for call to 'UNDIR_W_EDGE::UNDIR_W_EDGE(const UNDIR_W_EDGE&)' { ::new((void *)__p) _Up(std::forward<Args>(_args)...); }

The Code

GRAPH.h file

#include "vector"

template <typename Edge>
class GRAPH {
 private:
 // Implementation-dependent code
int Vcnt;
int Ecnt;
std::vector<std::vector< Edge > > adj;
 public:
GRAPH(int x):Vcnt(x),Ecnt(0) {

    adj.resize(Vcnt);
}
 virtual ~GRAPH();
 virtual int V() const;
 virtual int E() const;
 virtual void addEdge(const Edge &e){
    adj[e.V()].push_back(e);
    adj[e.W()].push_back(e);
    Ecnt++;
 };
 virtual std::vector< Edge > adjIterator(int) const;
};

UNDIRWEDGE.h file

 class UNDIR_W_EDGE {
    int v,w;
    float weight;

    public:
     UNDIR_W_EDGE(int v, int w, float weight);
     UNDIR_W_EDGE(UNDIR_W_EDGE &);
     virtual ~UNDIR_W_EDGE();
     virtual int V()const;
     virtual int W()const;
     virtual float WEIGHT()const;
     virtual int CompareTo(UNDIR_W_EDGE e)const;
    };

in UNDIRWEDGE.cpp

inline int UNDIR_W_EDGE::CompareTo(UNDIR_W_EDGE e)const{
if(this->weight > e.weight) return 1;
else if (this->weight < e.weight)return -1;
else                            return 0;
}  

in main.cpp

GRAPH<UNDIR_W_EDGE> g(10);
UNDIR_W_EDGE e(0,7,0.0);
g.addEdge(e);

Answer 1

You don't have a copy constructor for UNDIR_W_EDGE.

The copy constructor is required inside std::vector<UNDIR_W_EDGE>, as well as in CompareTo which takes its argument by value (for some reason).

You do have this:

UNDIR_W_EDGE(UNDIR_W_EDGE &);

Presumably you intended for it to be:

UNDIR_W_EDGE(const UNDIR_W_EDGE&);