Thread: Inherited class constructor

I have three classes 1 base and two inherited.. problem is when I try to initialize the it says undefined reference to vtable constructor.Any help? thanks in advance.

Code:

#ifndef QUOTE_H_INCLUDED
#define QUOTE_H_INCLUDED
#include <string>
using namespace std;
class Quote{
public:
    Quote()=default;
    //Quote(Quote &q):bookNo(q.bookNo),price(q.price) { }
    Quote(const string &book,double sales_price):bookNo(book),price(sales_price){}
    string isbn() const {return bookNo;}
    virtual double net_price(size_t n) const {return n*price;}
    virtual ~Quote()=default;
    static int max;
    virtual void debug();
private:
    string bookNo;
protected:
    double price=0.0;
};
class Disc_quote:public Quote{
public:
    Disc_quote() = default;
    Disc_quote(const string &book, double price,size_t qty, double disc ): Quote(book,price), quantity(qty),discount(disc) {}
    double net_price(size_t) const = 0 ;
    //Disc_quote(Disc_quote &d):Quote(d),quantity(d.quantity),discount(d.discount) { }
protected:
    size_t quantity = 0;
    double discount = 0;
};
class Bulk_quote:public Disc_quote{
public:
    //Bulk_quote(Bulk_quote &b):Disc_quote(b){}
    Bulk_quote(const string&  book,double p,size_t qty,double disc):Disc_quote(book,p,qty,disc) { }
    double net_price(size_t n) const override;
    void debug() override;
    
};
class No_disc : public Disc_quote    {
public:
    No_disc(const string &s,double price,size_t qt,double disc):Disc_quote(s,price,qt,disc) { }
    double net_price(size_t n) const override {
        if(quantity>100)
            return price*quantity;
        else
            return price*quantity*(1-discount);
    
    }

};
double print_total(ostream &os,const Quote &item,size_t n);
#endif // QUOTE_H_INCLUDED

when I try to declare such as
Bulk_quote("A",1,1,1) it gives error at line 34 that undefined reference to vtable for bulk_quote

This error usually means you haven't implemented a virtual destructor.
Have you implemented virtual ~Quote() ?

Kurt

Edit: Sorry it's not the missing destructor that is declared as default
It's propably any of the other virtual functions you haven't implemented or declared as override and not implemented.