Question

My have three .cpp files and their headers.

    //a.cpp
#include "a.h"
#include "b.h"
void A::foo() {
    C c;
    c.bar();
}


    //a.h
#include "b.h"
class A {
public:
    void foo();
};


    //b.h
#include "c.h"

    //c.h
#pragma once    
class C {
public:
    void bar();
};


    //c.cpp
#include "c.h"
void C::bar() {}

    //other files are ignored

But when I compiled them, I got this error:

a.cpp:(.text+0xb1): undefined reference to `C::bar()`

Have I included c.h through b.h? Why doesn’t it work?

Answer 1

An undefined reference is a linker error, your code is compiling. Make sure you are linking a.obj, b.obj and c.obj.