c Linker error undefined reference to vtable-CodePudding

I'm trying to write a small C inheritance program, after compiling succeeds, the linker fails in the derived of a derived class, C.o, stating

relocation against `_ZTV26C' in read-only section `.text'

and

undefined reference to `vtable for C'

can anyone see what am i missing?

A.h

#ifndef A_H_
#define A_H_
#include <string>
#include <iostream>
using namespace std;

class A {
protected:
    string name;
public:
    A(string name);
    virtual ~A();
    virtual void justATest(){}
    void justBecause();
    virtual bool derivedTest(){}
};

#endif /* A_H_ */

A.cpp

#include "A.h"

A::A(string name) {this->name.assign(name);}

A::~A() {}

void A::justBecause(){}

B.h

#ifndef B_H_
#define B_H_
#include "A.h"
#include <string>

class B : public A{
public:
    B(string name):A(name){}
    virtual ~B(){}
    bool derivedTest();
};

#endif /* B_H_ */

B.cpp

#include "B.h"
bool B::derivedTest()
{
    return true;
}

C.h

#ifndef C_H_
#define C_H_
#include "B.h"

class C : public B{
public:
    C(string name) :B(name){}
    virtual ~C(){}
    void justATest();
};

#endif /* C_H_ */

C.cpp

#include "C.h"
void C::justATest()
{
    cout<< this->name;
}

main.cpp

#include "C.h"
int main(int argc, char* argv[]) {
    C* c = new C("str");
return 0;
}

the exact error message is: /usr/bin/ld: ./main.o: warning: relocation against _ZTV1C' in read-only section .text._ZN1CC2ENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE[_ZN1CC5ENSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE]' /usr/bin/ld: ./main.o: in function C::C(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >)': /home/some_user/eclipse-workspace/demo_proj/Debug/../C.h:14: undefined reference to vtable for C' /usr/bin/ld: warning: creating DT_TEXTREL in a PIE

CodePudding user response：

After many hours of debugging, and countless tries, with the same error message i found the answer. This is C linker crooked way of telling me there is an unimplemented method in one of my classes. adding to c.h

bool derivedTest() override;

and to c.cpp

bool C::derivedTest(){return false;}

p.s another nice way of finding the problem is adding override after each message in the header file, the compiler is much clearer

CodePudding user response：

Please update your original question with the linker command and error message from the comments section.

To me it seems you are not using g for linking but rather ld. Configure eclipse to use g for linking your C source code then it should work.