如何解决C ++中未定义的参考错误？

Question

无法编译我的程序，因为它会给我“未定义的引用”错误。

ide中没有语法错误，所以我不知道是什么引起了问题。

#include <iostream>
#include <string>
#include <cmath>
#include <vector>

using namespace std;

//classes
class coordinates;
class ShapeTwoD;
class Rectangle;

//declare functions
void choice1();

//vectors
vector<coordinates>coordinatesVec;
vector<ShapeTwoD*>ShapeTwoDVec;

class coordinates
{
    private:
        int x, y;   
    public:
        coordinates(int x, int y)
        {
            this->x=1;
            this->y=1;
        }

        void setX(int y)
        {
            this->x=x;          
        }

        void setY(int y)
        {
            this->y=y;
        }

        int getX()
        {
            return x;
        }

        int getY()
        {
            return y;
        }
};

class ShapeTwoD
{
    protected:
        string name;
        bool containsWarpSpace;

    public:
        //default constructor       
        ShapeTwoD()
        {
            this->name = "";
            this->containsWarpSpace = false;
        };

        //other constructor
        ShapeTwoD(string name, bool containsWarpSpace)
        {
            this->name = name;
            this->containsWarpSpace = containsWarpSpace;
        }

        //copy constructor
        ShapeTwoD(const ShapeTwoD& s)
        {
            this->name = s.name;
            this->containsWarpSpace = s.containsWarpSpace;
        }

        //getname method
        string getName()
        {
            return name;
        }

        //getContainsWarpSpace method
        bool getContainsWarpSpace()     
        {
            return containsWarpSpace;
        }

        //setName
        void setName(string name)
        {
            this->name = name;
        }

        //setContainsWarpSpace
        void setContainsWarpSpace(bool containsWarpSpace)
        {
            this->containsWarpSpace = containsWarpSpace;
        }

        //Virtual methods
        virtual void setCoordinates(vector<coordinates>c) = 0;
        virtual double computeArea();
        virtual bool isPointInShape(int x, int y);
        virtual bool isPointOnShape(int x, int y);
        virtual string toString() = 0;
};//end of ShapeTwoD

class Rectangle: public ShapeTwoD
{

    private:
        vector<coordinates>vec;

    public:

        //constructor
        Rectangle()
        {

        }

        //set vector , the vector contains coordinates
        void setCoordinates(vector<coordinates>v)
        {
            this->vec=v;
        }

        //to find length of rectangle side based on 2 given (x,y)
        double distance(double x1, double x2, double y1, double y2)
        {
            return sqrt(pow(x2-x1,2)+pow(y2-y1,2));
        }

        //find area of rectangle
        double computeArea()
        {
            double length = distance(vec[1].getX(), vec[2].getX(), vec[1].getY(), vec[2].getY());
            double width = distance(vec[1].getX(), vec[0].getX(), vec[1].getY(), vec[0].getY());
            return length * width;
        }

        bool isPointInShape(int x, int y)
        {

            return true;
        }

        bool isPointOnShape(int x, int y)
        {
            return true;
        }

        string toString()
        {
            string x = "hello";
            return x;
        }
};//end of Rectangle

int main()
{   
    bool quit;
    while(quit == !true)
    {
        int option; //choice input
        cout << endl;
        cout << "Student ID    : 6348063" << endl;
        cout << "Student Name  : Sirikorn Chatphatthananan" << endl;
        cout << "------------------------------------------" << endl;
        cout << "Welcome to Assn2 program!" << endl;
        cout << endl;
        cout << "1)    Input sensor data" << endl;  
        cout << "2)    Compute area (for all records)" << endl;
        cout << "3)    Print shapes report" << endl;
        cout << "4)    Sort shape data" << endl;
        cout << "Please enter your choice: ";
        cin >> option;

        //enter choice "5" to quit the menu/program
        if(option == 5)
        {
            cout << endl;
            cout << "Quiting program....." << endl;
            cout << endl;
            quit = true;
        }

        if (option == 1)
        {
            choice1();
        }

        if (option == 2)
        {
            //at index 0 is the Rectangle object/pointer
            ShapeTwoDVec[0]->computeArea();

        }
    }
    //system("pause");
    return 0;
}//end of main()

void choice1()
{
    string shapename;
    string specialType;
    bool validShape = false;
    bool validType = false;

    cout << "[Input sensor data]" << endl;
    while (validShape != true)
    {       
        cout << "Please enter name of shape: ";
        cin >> shapename;

        if(shapename == "Rectangle" || shapename == "rectangle" )
        {
            //Create new ShapeTwoD object in heap
            ShapeTwoD* rectangleP = new Rectangle;
            int pointX, pointY;

            //Ask for special or normal type
            while(validType != true)
            {
                cout << "Please enter special type: ";
                cin >> specialType;

                if(specialType == "WS" || specialType == "ws")
                {
                    rectangleP->setContainsWarpSpace(true);
                    validType = true;
                }
                else if(specialType == "NS" || specialType == "ns")
                {
                    rectangleP->setContainsWarpSpace(false);
                    validType = true;
                }
                else
                {
                    cout << "Wrong input" << endl;
                }
            }

            try
            {
                //Register x and y coordinates for rectangle
                for(int i=1; i<=4; i++)
                {
                    cout << "Please enter x-ordinate of pt." << i <<": ";
                    cin >> pointX;
                    cout << "Please enter y-ordinate of pt." << i <<": ";
                    cin >> pointY;  

                    //Each looping will add new coordinates objects to vector
                    coordinates recCoordinates(pointX, pointY);
                    coordinatesVec.push_back(recCoordinates);
                }               
            }
            catch(const invalid_argument &err)
            {
                cerr << "All coordinates must be an int type";
            }           

            //Add items into Rectangle class in heap
            rectangleP->setName(shapename);
            rectangleP->setCoordinates(coordinatesVec);

            //To test for isPointOnShape
            //rectangleP->isPointOnShape(pointX, pointY);
            //rectangleP->isPointInShape(pointX, pointY);

            //Add all pointers into vector of ShapeTwoD
            ShapeTwoDVec.push_back(rectangleP);
        }
    }
}//end of function for choice1

期望用户根据形状输入一些坐标。选项1要求输入坐标，然后程序会将其保存到向量中。选项2将使用这些坐标来计算不同形状的面积。