C++ expected class-name before { token, an inheritance error - c++

Question

KSetBase.h base class , an interface
#ifndef HW6_GTUSETBASE_H
#define HW6_GTUSETBASE_H
class KSet;
#include <cstddef>
namespace TU {
template<typename T>
class KSetBase {
public:
virtual bool empty() const = 0;
virtual size_t size() const = 0; //int is not okay since unsigned also could be in.
//comparisons would be not working if that was case
//detailed
//https://stackoverflow.com/questions/1181079/stringsize-type-instead-of-int
virtual size_t max_size() const = 0;
virtual void insert(T first, T second) = 0; //cift dondurmesi gerekli
virtual void erase(T deleter) = 0;
virtual void clear() = 0;
virtual T find(T deneme) = 0;
virtual size_t count(T testle) = 0;
virtual T begin() = 0;
virtual T end() = 0;
protected:
~GTUSetBase() {
//do nothing
}
};
}
#endif //HW6_GTUSETBASE_H
KSet.h (derived class)
#include "KSetBase.h"
#ifndef HW6_GTUSET_H
#define HW6_GTUSET_H
#include <memory>
using namespace std;
namespace TU {
template<typename T>
class KSet : public KSetBase {
public:
bool empty() const;
size_t size() const;
size_t max_size() const;
void insert(T first);
void erase(T deleter);
void clear();
T find(T deneme);
size_t count(T testle);
T begin();
T end();
protected:
int hmany = 0;
shared_ptr<T> set_harmony;
};
}
#endif //HW6_GTUSET_H
I cant figure out what part of my code is wrong. I basically made a basic inheritance from interface class, which i implemented all functions in KSet.cpp. In theory nothing looks wrong but it gives 2 errors.
both in main.cpp and KSet.cpp
class KSet : public KSetBase {
Error line is this.
I checked #ifndef and #defines, i thought about using forward declaration but i cant seems to work that out.I am really stuck with this problem. I searched whole web about it , in the end there's always a big error on syntax or something that is visible , but i can't figure out on mine. It's very short and simple code.

Answer 1

KSetBase is a template class, if you inherit from it you must specify a template argument:
template<typename T>
class KSet : public KSetBase<T>
In addition, it seems you have a typo in the base class destructor.