c++虚函数调用及使用

#include <iostream>
using namespace std;
class A
{
public:
        virtual int print()=;
};
class B: public A
{
public:
        virtual int get()=;
        virtual int print()
        {
                cout<<get()<<endl;
        }
};
class C: public B
{
public:
        int get()
        {
                return ;
        }
};
int func(A* a)
{
        a->print();
}
int main()
{
        C c;
        func(&c);
        return ;
}