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    // Shape.h -- this would be A.dll
    #pragma once
 
    // Notice the conditional
    #ifdef SHAPE_EXPORTS
    #define SHAPE_API __declspec(dllexport)
    #else
    #define SHAPE_API __declspec(dllimport)
    #endif
 
    class SHAPE_API Shape /*: public IShape*/
    {
    public:
        Shape();
        Shape(int sides, int sideLength, int apothem);
        ~Shape();
 
        int Perimeter();
        double Area();
    private:
        int sides;
        int sideLength;
        int apothem;
    };
 
    // Shape.cpp
 
    // Do it before including the header to get dllexport
    #define SHAPE_EXPORTS
 
    #include "stdafx.h"
    #include "Shape.h"
 
    Shape::Shape() : sides(0), sideLength(0), apothem(0)
    {
    }
 
    Shape::Shape(int sides, int sideLength, int apothem) : sides(sides), sideLength(sideLength), apothem(apothem)
    {
    }
 
    Shape::~Shape()
    {
    }
 
    double Shape::Area()
    {
        if (sides == 1 || sides == 2)
        {
            return -1;
        }
 
        return .5 * Perimeter() * apothem;
    }
 
    int Shape::Perimeter()
    {
        return sideLength * sides;
    }
 
    // ShapesTester.h - this would be B.dll
    #include "../TestHarness/ITest.h"
 
    class ShapesTester : ITest
    {
    public:
        ShapesTester();
        ~ShapesTester();
 
        bool Test() override;
        ShapesTester & ShapesTesterFactory();
 
    private:
    };
 
    // ShapesTester.cpp
    #include "stdafx.h"
    #include "ShapesTester.h"
    #include "Shape.h"
 
    ShapesTester::ShapesTester()
    {
    }
 
 
    ShapesTester::~ShapesTester()
    {
    }
 
    bool ShapesTester::Test()
    {
        Shape myShape = Shape(3, 9, 5); // error here; Cannot resolve symbol 'Shape'
 
        return myShape.Area() == 67.5;
    }
 
    ShapesTester & ShapesTesterFactory()
    {
        ShapesTester * tester = new ShapesTester();
 
        return *tester;
    }