Can't access the header included in another header?

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?

Sorry looks like I forget to clean some old object files. I should run `make clean` first... It's a unqualified question indeed. — Lai Yu-Hsuan, Jun 20 '12 at 17:15

score 7 · Accepted Answer · answered Jun 20 '12 at 17:10

7

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

answered Jun 20 '12 at 17:10

IronMensan

6,761
1
26
35

score 2 · Answer 2 · answered Jun 20 '12 at 17:14

2

This is a link error, indicating that the definition of C::bar() is missing from the set of translation units that are linked to build the program. The most likely reason is that you're not including c.cpp in your build.

answered Jun 20 '12 at 17:14

Mike Seymour

249,747
28
448
644

Can't access the header included in another header?

2 Answers2