Possible Class/Destructor setup issue, receiving error message 'unresolved external symbol'

Question

EDIT: I believe my issue is because I'm calling my FacePoint class from an .exe project, and FacePoint is actually located in a .dll project, both within the same solution. Any idea to combat this?

I have a class called FacePoint which gets and sets X and Y values of a face feature.

This is FacePoint.h:

 #pragma once
class FacePoint
{
public:
    FacePoint(void);
    FacePoint(int X, int Y);

    void FacePoint::SetX(int X);
    void FacePoint::SetY(int Y);
    void FacePoint::SetXY(int X, int Y);

    int FacePoint::GetX();
    int FacePoint::GetY();

    ~FacePoint(void);

 private:
    int coordX;
    int coordY;
};

...and FacePoint.cpp:

#include "StdAfx.h"
#include "FacePoint.h"

FacePoint::FacePoint(void)
{
    coordX = 0;
    coordY = 0;
}

FacePoint::FacePoint(int X, int Y)
{
    coordX = X;
    coordY = Y;
}

void FacePoint::SetX(int X){ coordX = X; }

void FacePoint::SetY(int Y){ coordY = Y; }

void FacePoint::SetXY(int X, int Y)
{
    coordX = X;
    coordY = Y;
}

int FacePoint::GetX(){ return coordX; }

int FacePoint::GetY(){ return coordY; }

FacePoint::~FacePoint(){}

This seems OK to me, however when I try to implement a vector of FacePoint objects, as follows:

    std::vector<FacePoint> point;
    result = GetFeaturePoints(pHandle, &point);
    int x = 0;
    int y = 0;
    for(int p = 0; p < point.size(); p++)
    {
        x = point[p].GetX();
        y = point[p].GetY();
    }

I get the following compile-time errors:

Error 37 error LNK1120: 3 unresolved externals

Error 36 error LNK2001: unresolved external symbol "public: __thiscall FacePoint::~FacePoint(void)" (??1FacePoint@@QAE@XZ)

Error 35 error LNK2001: unresolved external symbol "public: int __thiscall FacePoint::GetX(void)" (?GetX@FacePoint@@QAEHXZ)

Error 34 error LNK2001: unresolved external symbol "public: int __thiscall FacePoint::GetY(void)" (?GetY@FacePoint@@QAEHXZ)

I'm not sure why this is happening, but from the error messages, I suspect it's something to do with my destructor?...

I searched around and most of these issues were around missing a constructor/destructor definition. To my knowledge, my constructor seems fine, and the error message seems to hint at the destructor. The only thing I can think of is I'm missing a desctructor which destroys int X, int Y, but I didn't think primitives needed that?...

Any help is appreciated. Thank you!!

EDIT: So I forgot to #include "FacePoint.h" in my main (where I am creating the vector of FacePoint). I added that in, but am receiving this compile-time error message:

Error 4 error LNK2019: unresolved external symbol "public: __thiscall FacePoint::~FacePoint(void)" (??1FacePoint@@QAE@XZ) referenced in function "public: void * __thiscall FacePoint::`scalar deleting destructor'(unsigned int)" (??_GFacePoint@@QAEPAXI@Z)

Any idea, guys? Thanks!

Mark Ransom Mark Ransom · Accepted Answer · 2014-10-03T05:25:04

It looks like FacePoint.cpp is not part of your project. That would mean that the linker can't find the body of code that implements those functions.

Possible Class/Destructor setup issue, receiving error message 'unresolved external symbol'

2 Answers