Problem compiling C++ program

Question

Hi, there! I'm writting graph classes. I've wrote such code in "Graphs.h" :

#include <vector>
#include <iostream>
using namespace std;

struct Edge{
 int v,w;
 Edge(int v=-1, int w=-1):v(v),w(w){}
};

class Graph
{
protected:
 int Ecnt, Vcnt; bool digraph;
public:
 Graph(int V, bool isDirected) :Ecnt(0),Vcnt(V),digraph(isDirected) {}
 ~Graph();
 virtual int V() const;
 virtual int E() const;
 virtual bool directed() const;
 virtual void insert(Edge);
 virtual void remove(Edge) = 0;
 virtual bool edge(int, int);
 class adjIterator
 {
 public:
  adjIterator(const Graph &, int);
  int beg();
  int nxt();
  bool end();
 };
};


class DenseGraph:public Graph
{
private:
 int Vcnt,Ecnt; bool digraph;
 vector <vector <bool> > adj;
public:
 DenseGraph(int V, bool digraph=false) : Graph(V,digraph),adj(V)
   {
    for(int i=0;i<V;++i)
     adj[i].assign(V,false);
   }
   int  V() const{ return Vcnt;}
   int E() const{return Ecnt;}
   bool  directed() { return digraph;}
   void  insert(Edge e) 
   {
    int v=e.v, w=e.w;
    if(adj[v][w]==false) Ecnt++;
    adj[v][w]=true;
    if(!digraph) adj[w][v]=true;
   }
   void remove(Edge e)
   {
    int v=e.v, w=e.w;
    if(adj[v][w]==true) Ecnt--;
    adj[v][w]=false;
    if(!digraph) adj[w][v]=false;
   }
   bool edge(int v,int w) const
   {
    return adj[v][w];
   }
   class adjIterator;
   friend class adjIterator;
};

class DenseGraph::adjIterator
{
 const DenseGraph &G;
 int i,v;
public:
 adjIterator(const DenseGraph &G, int v): G(G), v(v), i(-1) 
 { }
 int beg()
 { i=-1; return nxt();}
 int nxt()
 {
  for(i++;i<G.V();i++)
   if(G.adj[v][i]==true) return i;
  return-1;
 }
 bool end()
 { return i>= G.V();}
};

class SparseMultiGraph:public Graph
{

 struct node{
  int v; node* next;
  node(int x, node* t){v=x; next=t;}
 };
 typedef  node* link;
 vector <link> adj;
public:
 SparseMultiGraph(int V, bool digraph=false): Graph(V,digraph),adj(V)
   { adj.assign(V,0);}
   int V() const{ return Vcnt;}
   int E() const{return Ecnt;}
   bool directed() const{return digraph;}
   void insert(Edge e)
   {
    int v=e.v,w=e.w;
    adj[v]=new node(w,adj[v]);
    if(!digraph)
     adj[w]=new node(v,adj[w]);
    Ecnt++;
   }
   void remove(Edge e)
   {
    //  int v=e.v,w=e.w;

   }
   bool edge(int v, int w) const;
   class adjIterator;
   friend class adjIterator;
};

class SparseMultiGraph::adjIterator
{
 const SparseMultiGraph &G;
 int v;
 SparseMultiGraph::link t;
public:
 adjIterator(const SparseMultiGraph &G, int v):
   G(G), v(v) {t = 0;}
   int beg()
   {   t=G.adj[v]; return t? t->v: -1;}
   int nxt()
   { if(t) t=t->next; return t? t->v: -1;}
   bool end()
   { return t==0;}
};

template<class Graph>
class IO
{
public:
 static void show(const Graph &);
 static void scanEZ(Graph &);
 static void scan(Graph &);
};




template<class Graph>
class CC
{
public:
 CC(const Graph &);
 int count();
 bool connect(int ,int );
};


//return all edges included in this Graph object G
template<class Graph>
vector< Edge> edges(Graph &G)
{
 int E=0;
 vector <Edge> a(G.E());
 for(int v=0;v<G.V();++v)
 {
  typename Graph::adjIterator A(G,v);
  for(int w=A.beg(); !A.end(); w=A.nxt())
   if(G.directed() || v<w)
    a[E++]=Edge(v,w);
 }
 return a;
}

template<class Graph>
void IO<Graph>::show(const Graph &G)
{
 for(int s=0;s<G.V(); ++s)
 {
  cout.width(2); cout<<s<<":";
  typename Graph::adjIterator A(G,s);
  for(int t=A.beg(); !A.end(); t=A.nxt())
  { cout.width(2); cout<<t<<" ";}
  cout<< endl;
 }
}

//17_12
template<class Graph>
static void randE(Graph& G, int E)
{
 for(int i=0;i<E;++i)
 {
  int v=int(G.V()*rand()/(1.0+RAND_MAX));
  int w=int(G.V()*rand()/(1.0+RAND_MAX));
  G.insert(Edge(v,w));
 }
}

//17_13
template<class Graph>
static void randG(Graph &G, int E)
{
 double p=2.0*E/G.V()/(G.V()-1);
 for(int i=0;i<G.V();++i)
  for(int j=0;j<i;++j)
   if(rand()<p*RAND_MAX)
    G.insert(Edge(i,j));
}

and in Test.cpp

#include "stdafx.h"
#include <stdlib.h>
#include "Graph_7_1.h"
using namespace std;

void _tmain(int argc, char* argv[])
{
 int V=atoi(argv[1]);
 Graph* G= new DenseGraph(V) ;
 IO<Graph>::scan(*G);
 if(V<20) IO<Graph>::show(*G);
 cout<<G->E()<<" edges ";
 CC<Graph> Gcc(*G);
 cout<< Gcc.count() <<" components"<<endl;
}

And I've got such errors list:

error LNK1120: 13 unresolved externals C:\Users\Роман\documents\visual studio 2010\Projects\TestGraph\Debug\TestGraph.exe TestGraph
error LNK2001: unresolved external symbol "public: virtual bool __thiscall Graph::directed(void)const " (?directed@Graph@@UBE_NXZ) C:\Users\Роман\documents\visual studio 2010\Projects\TestGraph\TestGraph\TestGraph.obj TestGraph
error LNK2001: unresolved external symbol "public: virtual bool __thiscall Graph::edge(int,int)" (?edge@Graph@@UAE_NHH@Z) C:\Users\Роман\documents\visual studio 2010\Projects\TestGraph\TestGraph\TestGraph.obj TestGraph
error LNK2001: unresolved external symbol "public: virtual int __thiscall Graph::E(void)const " (?E@Graph@@UBEHXZ) C:\Users\Роман\documents\visual studio 2010\Projects\TestGraph\TestGraph\TestGraph.obj TestGraph
error LNK2001: unresolved external symbol "public: virtual int __thiscall Graph::V(void)const " (?V@Graph@@UBEHXZ) C:\Users\Роман\documents\visual studio 2010\Projects\TestGraph\TestGraph\TestGraph.obj TestGraph
error LNK2001: unresolved external symbol "public: virtual void __thiscall Graph::insert(struct Edge)" (?insert@Graph@@UAEXUEdge@@@Z) C:\Users\Роман\documents\visual studio 2010\Projects\TestGraph\TestGraph\TestGraph.obj TestGraph
error LNK2019: unresolved external symbol "public: __thiscall CC<class Graph>::CC<class Graph>(class Graph const &)" (??0?$CC@VGraph@@@@QAE@ABVGraph@@@Z) referenced in function _wmain C:\Users\Роман\documents\visual studio 2010\Projects\TestGraph\TestGraph\TestGraph.obj TestGraph
error LNK2019: unresolved external symbol "public: __thiscall Graph::~Graph(void)" (??1Graph@@QAE@XZ) referenced in function __unwindfunclet$??0DenseGraph@@QAE@H_N@Z$0 C:\Users\Роман\documents\visual studio 2010\Projects\TestGraph\TestGraph\TestGraph.obj TestGraph
error LNK2019: unresolved external symbol "public: __thiscall Graph::adjIterator::adjIterator(class Graph const &,int)" (??0adjIterator@Graph@@QAE@ABV1@H@Z) referenced in function "public: static void __cdecl IO<class Graph>::show(class Graph const &)" (?show@?$IO@VGraph@@@@SAXABVGraph@@@Z) C:\Users\Роман\documents\visual studio 2010\Projects\TestGraph\TestGraph\TestGraph.obj TestGraph
error LNK2019: unresolved external symbol "public: bool __thiscall Graph::adjIterator::end(void)" (?end@adjIterator@Graph@@QAE_NXZ) referenced in function "public: static void __cdecl IO<class Graph>::show(class Graph const &)" (?show@?$IO@VGraph@@@@SAXABVGraph@@@Z) C:\Users\Роман\documents\visual studio 2010\Projects\TestGraph\TestGraph\TestGraph.obj TestGraph
error LNK2019: unresolved external symbol "public: int __thiscall CC<class Graph>::count(void)" (?count@?$CC@VGraph@@@@QAEHXZ) referenced in function _wmain C:\Users\Роман\documents\visual studio 2010\Projects\TestGraph\TestGraph\TestGraph.obj TestGraph
error LNK2019: unresolved external symbol "public: int __thiscall Graph::adjIterator::beg(void)" (?beg@adjIterator@Graph@@QAEHXZ) referenced in function "public: static void __cdecl IO<class Graph>::show(class Graph const &)" (?show@?$IO@VGraph@@@@SAXABVGraph@@@Z) C:\Users\Роман\documents\visual studio 2010\Projects\TestGraph\TestGraph\TestGraph.obj TestGraph
error LNK2019: unresolved external symbol "public: int __thiscall Graph::adjIterator::nxt(void)" (?nxt@adjIterator@Graph@@QAEHXZ) referenced in function "public: static void __cdecl IO<class Graph>::show(class Graph const &)" (?show@?$IO@VGraph@@@@SAXABVGraph@@@Z) C:\Users\Роман\documents\visual studio 2010\Projects\TestGraph\TestGraph\TestGraph.obj TestGraph
error LNK2019: unresolved external symbol "public: static void __cdecl IO<class Graph>::scan(class Graph &)" (?scan@?$IO@VGraph@@@@SAXAAVGraph@@@Z) referenced in function _wmain C:\Users\Роман\documents\visual studio 2010\Projects\TestGraph\TestGraph\TestGraph.obj TestGraph

Could someone help me? Thanks!

Answer 1

You have not defined the member function Graph::directed. Either define it or make it pure virtual:

 virtual bool directed() const = 0;

Same for other errors.

Answer 2

You either have to implement all those functions (Graph::directed(), etc. etc.) or declare them pure virtual.