Unresolved external symbol error when using multiple directories with c++ project

Question

Hello, I'm having an issue where VS is throwing an unresolved external symbol error and I'm not sure how to resolve this.

Error: LNK2019 unresolved external symbol "public: __thiscall coppercable::coppercable(void)" (??0coppercable@@QAE@XZ) referenced in function _main NetworkStackMain C:\Users\JoshS\OneDrive\NetworkStack\NetworkStack\NetworkStackMain\NetworkStackMain.obj 1

After a few searches this seems to commonly be due to the linker being unable to find this function declaration. I attempted to add the directories of the file containing the function the error is referring to, coppercable::coppercable(), but this did not help.

Here is the location of my VS project files, per the error

]2

And here is the location of the file containing the function declaration, note the definition is in a cpp file in /source instead of /header

Code in main:

#include <iostream>  
#include "cable.hpp"  
#include "coppercable.hpp"  

using namespace std;  

int main()  
{  
    cable* cable1 = new coppercable();  
    cable1->setCableDiameter(0.2893);  
    cable1->setCableLength(5);  
    cout << cable1->getAwgRating();  
}  

Header file with function declaration:

#include <iostream>  
using namespace std;  

class coppercable : public cable  
{  
    public:  
        coppercable();  
        ~coppercable();  
        double getPowerLoss() override;  
};  

Source file with function definition:

#include "../header/coppercable.hpp"  
#include "../header/copperwire.hpp"  
#include <iostream>  
#include <math.h>  
using namespace std;  

coppercable::coppercable()  
{  

}  

And for project properties, I've tried adding multiple directories including the exact directory where the source and header files are which contain the functions declaration/definition

Has anyone experienced this kind of issue based on this scenario? Any pointers or ideas is appreciated, thank you!

Answer 1

Probably you must add coppercable.cpp and maybe other .cpp files to your project. Right-click Source Files or project node in Solution Explorer, go to Add, Existing Item and select the file.

The longer way: create a Static Library or DLL, which can be used in many main projects.

Answer 2

Hi jjs,

The LNK2019 often means that your declaration is not defined. You can try to add the directories of source files in VC++ Directories/Source Directories.

Best Regards,
Dylan

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