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Undefined Reference in virtual functions and inheritance classes

titan88 (17)
I am having difficulties with compiling the these two programs together. I get no errors when compiling the function file and the main into .o object files but when compiling together I get undefined reference to the constructors and functions. Why is this, what am I missing? Thanks!
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#ifndef SHAPE_H
#define SHAPE_H

#include <iostream>
#include <string>

using namespace std;

const double PI = 3.14159265359;
//Base Class---------------------------------------------
class Shape {
    protected:
        //Dimensions
        double d1;
        double d2;
        int NumberDimensions;
    public:
        //Default Constructor
        Shape();
        //regular constructor
        Shape( double d );
        //Destructor
        ~Shape();
        //setters / getters
        double get_d1() { return d1; }
        double get_d2() { return d2; }
        double get_NumberDimensions() { return NumberDimensions; }
        void set_d1(double x) { d1 = x; }
        void set_d2(double x) { d2 = x; }
        //virtual function
        virtual double getArea();
        virtual string getName();
        virtual double getVolume();
};
//Shape Type-----------------------------------------------
class TwoDimensionalShape : public Shape { 
    public:
        TwoDimensionalShape();
};

class ThreeDimensionalshape : public Shape {
    protected:
        double d3;
    public:
        ThreeDimensionalshape();
        double get_d3() { return d3; }
        void set_d3(double x) { d3 = x; }   
};
//two dimensionals Shape classes-------------------------
class Circle : public TwoDimensionalShape {
    public:
        Circle(); //default constructor
        Circle( double r); //regular constructor
        double getArea(); //get area function
        string getName(); //get name of shape
};
class Square : public TwoDimensionalShape {
    public:
        Square();
        Square(double dim);
        virtual double getArea();
        virtual string getName(); 
};
class Triangle : public TwoDimensionalShape {
    public:
        Triangle();
        Triangle(double dim, double dim2); 
        virtual double getArea();
        virtual string getName(); 
};
//three dimensional shape classes-------------------------
class Sphere : public ThreeDimensionalshape {
    public:
        Sphere();
        Sphere(double dim);
        virtual double getArea();
        virtual double getVolume();
        virtual string getName();
};
class Cube : public ThreeDimensionalshape{
    public:
        Cube();
        Cube(double dim);
        virtual double getArea();
        virtual double getVolume();
        virtual string getName();   
};
class Tetrahedron : public ThreeDimensionalshape{
    public:
        Tetrahedron();
        Tetrahedron(double dim);
        virtual double getArea();
        virtual double getVolume();
        virtual string getName();
};



  #endif
    //--------------------------------------------------------- 


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

#include "shape.h" //header file

using namespace std;
//----------------------------------------------
//Default constructor
Shape::Shape() { 
	d1 = 0;
	d2 = 0;
}

//Two dimensional shapes-----------------------------------
/*TwoDimensionalShape::TwoDimensionalShape() {
	NumberDimensions = 2 ;
 }*/
//Default constructor--------------------
Circle::Circle() { 
	d1 = 1;
	NumberDimensions = 2;
}
//Regular constructor--------------------
Circle::Circle( double r ) {
	d1 = r;
	NumberDimensions = 2;
}
//--
double Circle::getArea() {
	return PI * pow( d1, 2 );
}
//--
std::string Circle::getName() {
	return string("Circle");
}
//Default constructor--------------------
Square::Square() {
	d1 = 1 ;
	d2 = 1;
	NumberDimensions = 2;
}
//Regular constructor--------------------
Square::Square( double dim ) {
	d1 = dim;
	d2 = dim;
	NumberDimensions = 2;
}
//--
double Square::getArea() {
	return pow( d1, 2 );
}
//--
std::string Square::getName() {
	return string("Square");
}
//Default constructor--------------------
Triangle::Triangle() {
	d1 = 1;
	d2 = 1;
	NumberDimensions = 2;
}
//Regular constructor--------------------
Triangle::Triangle(double dim, double dim2) {
	d1 = dim;
	d2 = dim2;
	NumberDimensions = 2;
}
//--
double Triangle::getArea() {
	return (d1 * d2) / 2;
}
//--
std::string Triangle::getName() {
	return string("Triangle");
}
//Three dimensional shapes-----------------------------------
/*ThreeDimensionalshape::ThreeDimensionalshape() { 
	NumberDimensions = 3 ;
}*/
//Default constructor---------------------
Sphere::Sphere() {
	d1 = 1;
	d2 = 1;
	d3 = 1;
	NumberDimensions = 2;
}
//Regular constructor---------------------
Sphere::Sphere(double dim) {
	d1 = dim;
	d2 = dim;
	d3 = dim;
	NumberDimensions = 2;
}
//--
double Sphere::getArea(){
	return 4 * PI * pow( d1, 2 );
}
//--
double Sphere::getVolume(){
	return (4/3) * PI * pow( d1, 3 );
}
//--
std::string Sphere::getName() {
	return string("Sphere");
}
//Default constructor---------------------
Cube::Cube(){
	d1 = 1;
	d2 = 1;
	d3 = 1;
	NumberDimensions = 2;
}
//Regular constructor---------------------
Cube::Cube(double dim){
	d1 = dim;
	d2 = dim;
	d3 = dim;
	NumberDimensions = 2;
}
//--
double Cube::getArea(){
	return pow( d1, 2 );
}
//--
double Cube::getVolume(){
	return pow( d1, 3 );
}
//--
std::string Cube::getName() {
	return string("Cube");
}
//Default constructor---------------------
Tetrahedron::Tetrahedron(){
	d1 = 1;
	d2 = 1;
	d3 = 1;
	NumberDimensions = 2;
}
//Regular constructor---------------------
Tetrahedron::Tetrahedron(double dim){
	d1 = dim;
	d2 = dim;
	d3 = dim;
	NumberDimensions = 2;
}
//--
double Tetrahedron::getArea(){
	return sqrt(3) * pow( d1, 2);
}
//--
double Tetrahedron::getVolume(){
	return pow(d1, 3) / (6 * sqrt(2));
}
//--
std::string Tetrahedron::getName() {
	return string("Tetrahedron");
}


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#include "shape.h" //header file

using namespace std;

int main() {
//Pointer Array--------------------------------------------
	Shape* arr[6];     //Assign Shape Dimensions and to Array
	Circle cir(2);     //declares value for circle ~ cir is var name
		arr[0] = &cir; //assigns cir var to array position 0
	Square sqr(3);
		arr[1] = &sqr;
	Triangle tri(4, 2);
		arr[2] = &tri;	
	Sphere sph(5);
		arr[3] = &sph;
	Cube cb(6);
		arr[4] = &cb;
	Tetrahedron trhd(7);
		arr[5] = &trhd;
//Loop each index of array and perform calculation
	for (int i = 0; i < 6; ++i) {
		cout << "\n Shape Name: \n" << arr[i]->getName() 
			 << " with area = " << arr[i]->getArea();
			 if ( arr[i]->get_NumberDimensions() == 3 )
			 {
			 	cout <<"\n with volume = " << arr[i]->getVolume();
			 }
	}
}
Last edited on
ne555 (10692)
> I get undefined reference to the constructors and functions.
> Why is this, what am I missing?
http://www.cplusplus.com/forum/general/113904/#msg622050
You never defined those functions.

undefined reference to `Shape::getArea()'
undefined reference to `Shape::getName()'
undefined reference to `Shape::getVolume()'
undefined reference to `Shape::~Shape()'
undefined reference to `ThreeDimensionalshape::ThreeDimensionalshape()'
undefined reference to `TwoDimensionalShape::TwoDimensionalShape()'
get{Area,Name,Volume}() are virtual functions. If you do not intend to provide them a body, mark them as pure virtual
virtual double getArea() = 0;

you never defined the destructor for Shape. An empty one may suffice. Given that you've got virtual member functions, you ougth to mark the destructor as virtual too.
virtual ~Shape() = default;

You didn't provide a definition for the constructor of {Three,Two}DimensionalShape, ¿how the hell do you expect that to work?
Last edited on
titan88 (17)
So now declaring the virtuals as pure I get another error stating abstract type. Also how should I provide a constructor for TwoDimensionalShape and ThreeDimensionalShape? Isn't TwoDimensionalShape(); the default constructor?

~ Thanks

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main.cpp:13:9: error: cannot declare variable ‘cir’ to be of abstract type ‘Circle’
  Circle cir(2);     //declares value for circle ~ cir is var name
         ^
In file included from main.cpp:6:0:
shape.h:55:7: note:   because the following virtual functions are pure within ‘Circle’:
 class Circle : public TwoDimensionalShape {
       ^
shape.h:38:18: note: 	virtual double Shape::getVolume()
   virtual double getVolume() = 0;
                  ^
main.cpp:15:9: error: cannot declare variable ‘sqr’ to be of abstract type ‘Square’
  Square sqr(3);
         ^
In file included from main.cpp:6:0:
shape.h:62:7: note:   because the following virtual functions are pure within ‘Square’:
 class Square : public TwoDimensionalShape {
       ^
shape.h:38:18: note: 	virtual double Shape::getVolume()
   virtual double getVolume() = 0;
                  ^
main.cpp:17:11: error: cannot declare variable ‘tri’ to be of abstract type ‘Triangle’
  Triangle tri(4, 2);
           ^
In file included from main.cpp:6:0:
shape.h:69:7: note:   because the following virtual functions are pure within ‘Triangle’:
 class Triangle : public TwoDimensionalShape {
       ^
shape.h:38:18: note: 	virtual double Shape::getVolume()
   virtual double getVolume() = 0;
ne555 (10692)
> Isn't TwoDimensionalShape(); the default constructor?
If you don't declare any constructors, the compiler will provide default constructor for you.
If you declare a constructor that takes no parameters (e.g., TwoDimensionalShape();) then you need to provide a definition.
If the default behaviour was good enough for you, then you can mark it as such 
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class TwoDimensionalShape : public Shape { 
    public:
        TwoDimensionalShape() = default;
};


> error: cannot declare variable ‘cir’ to be of abstract type ‘Circle’
> because the following virtual functions are pure within ‘Circle’:
> virtual double getVolume() = 0;
you never defined how the volume of a circle/sqare/triangle should be computed.
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class TwoDimensionalShape : public Shape { 
    public:
        TwoDimensionalShape() = default;
        virtual double getVolume() override{
           return 0;
        }
};
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