Issue with circular dependency even after separating definitions

Question

Please see my previous post here:

Undefined type error even with forward declaration

I moved the definitions to cpp files and I still face the issue. Any ideas why? My files look like this:

Header1.hpp

#ifndef HEADER1_HPP
#define HEADER1_HPP

namespace sample_ns
{
    class sample_class{
    public:
        static int getNumber();
        static void print();    
    };
}
#endif

Header2.hpp

#ifndef HEADER2_HPP
#define HEADER2_HPP
namespace sample_ns
{
    class sample_class2{
    public:
        sample_class2();
        int getNumber2();
    };
}

#endif

Source1.cpp

#include "Header1.hpp"
#include "Header2.hpp"
#include "stdafx.h"
#include <iostream>
namespace sample_ns
{
        int sample_class::getNumber()
        {
            sample_class2 obj;
            return obj.getNumber2();
        }
        void sample_class::print()
        {
            std::cout << "Print utility function" << std::endl;
        }
}

Source2.cpp

#include "Header2.hpp"
#include "Header1.hpp"
#include "stdafx.h"
#include <iostream>
namespace sample_ns
{
        sample_class2::sample_class2()
        {
            sample_class::print();
        }
        int sample_class2::getNumber2()
        {
            sample_class::print();
            return 5;
        }
}

In my main I call it as:

 std::cout << sample_ns::sample_class::getNumber() << std::endl;

I get 'sample_class2' : undeclared identifier. I tried adding class sample_class2; but that still gives me error

EDIT: my main file:

#include "stdafx.h"
#include <iostream>
#include "Header1.hpp"

int _tmain(int argc, _TCHAR* argv[])
{
    std::cout << "hello" << std::endl;
    std::cout << sample_ns::sample_class::getNumber() << std::endl;

    return 0;
}

I think you should just use "using namespace sample_ns" in the cpp files instead of defining the functions in that namespace. It maybe won't fix the issue, but it is good style. — GeneralFailure, Oct 05 '15 at 18:56
It works fine for me. I can compile it. Please show, how you are actually invoking your compiler. — m8mble, Oct 05 '15 at 19:03
The files are part of VS console application project. I just build the solution — ashish g, Oct 05 '15 at 19:04
Your code runs fine for me if I just take out the stdafx.h from both source files and make change main to int main() — Zebrafish, Oct 05 '15 at 19:04
Thanks for that comment. Looks like some issue with precompiled headers. disabling that fixed the errors. Will look into precompiled headers now. — ashish g, Oct 05 '15 at 19:09
I am not completely sure about the precompiled headers. Will read more about them now. However, removing stdafx.h from source1 and source2, disabling precompiled headers option in project properties fixed the error. — ashish g, Oct 05 '15 at 19:12

JGC · Answer 1 · 2015-10-05T19:05:03.793

0

The best practice for declaring classes and namespaces in header and cpp files is using structure likes below:

Header1.hpp

#ifndef HEADER1_HPP
#define HEADER1_HPP
#include "Header2.hpp"
#include <iostream>

namespace sample_ns
{
    class sample_class{
    public:
        static int getNumber();
        static void print();    
    };
}
#endif

Source1.cpp

#include "Header1.hpp"
namespace sample_ns
{
        int sample_class::getNumber()
        {
            sample_class2 obj;
            return obj.getNumber2();
        }
        void sample_class::print()
        {
            std::cout << "Print utility function" << std::endl;
        }
}

So by including in header files and using ifndef you become sure that circular dependencies will not occure.

edited Oct 05 '15 at 19:05

answered Oct 05 '15 at 18:55

JGC

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`stdafx.h` does not belong in a header file and your headers are including themselves. – Captain Obvlious Oct 05 '15 at 18:56
You are recursively including Header1.hpp in Header1.hpp – NathanOliver Oct 05 '15 at 19:03
I don't think that's the problem, this runs perfectly fine for me if I take out the stdafx.h from both source files and change the entry to int main() or int main(int argc, char arg[]) – Zebrafish Oct 05 '15 at 19:09

Issue with circular dependency even after separating definitions

1 Answers1