Undefined reference to vtable

[George4ger]

I have to make a Chain of Mountains that contains other chains or simple mountains. For that reason I constructed a Class Mountain and then two sub-class. The subclass Chain and the subclass MountainSingle. The class chain contains itself a vector of pointers to other objects of type Mountain(Thus I have a vector containing pointers to other MountainSingle or Chain). My code is the following:

CLASS CHAIN


Chain* Chain::copie() const {
return (new Chain(*this));
}

Chain::Chain(Chain const & other){
for(auto element: other.ChainofChain){
ChainofChain.push_back(element->copie());
}
}

void Chain::dessine_sur(SupportADessin & support) const {
for(auto element: ChainofChain){
element->dessine_sur(support);// erwtisi avrio na teleiwnoume
}
}

std::vector<Mountain *> Chain::get_Chains() const
{
return ChainofChain;
}

double Chain::altitude(double x, double y) const {
double alt = 0;

for(auto element : ChainofChain)
{
if(element->altitude(x,y) > alt){ alt = element->altitude(x,y); }
}
return alt;
}




CLASS MOUNTAIN

#include<iostream>
#include "Dessinable.h"
#include "SupportADessin.h"

class Mountain:public Dessinable{
public:
virtual void dessine_sur(SupportADessin & support) const override= 0;
virtual Mountain* copie() const = 0;
virtual double altitude(double x, double y)const =0;
virtual ~Mountain(){}
};


But upon compilation I get the following error. I know that there are many other posts about the issue but even if I made the small adjustements proposed I still get the following error


Chain::Chain(Chain const & ): undefined reference to vtable for chain.


Thank you in advance

[seeplus]

My code is the following:

Part of your code is....

Without the rest of the classes, this can't be compiled.....

[mbozzi]

Typically the error means that you have declared but not defined the first virtual member function in class Chain.

For example this program exhibits the problem

struct a { virtual void f(); };
int main() {}

But this one does not:

struct a { virtual void f() {}; virtual void g(); };
int main() {}