#ifndef CIRCLE_H
#define CIRCLE_H
#include <QString>
#include <string>
using namespace std;
class Circle {
public:
//constructors
Circle();
Circle(double r);
//setter
void setRadius(double r);
//getter
double getRadius();
//calculate the diameter of a circle
double computeDiameter()const;
//calculate the area of a circle
double computeArea()const;
//calculate the Circumference of a circle
double computeCircumference()const;
//checks if radius of circle is bigger
**bool isBigger(const Circle& other) const;**
private:
//private data members
double m_Radius;
};
#endif // CIRCLE_H
#include "circle.h"
#include "math.h"
#include <iostream>
#include <QString>
#include <sstream>
using namespace std;
Circle::Circle()
{
m_Radius = 0;
}
Circle::Circle(double r)
{
m_Radius = r;
}
void Circle::setRadius(double r){
m_Radius = r ;
}
double Circle::getRadius(){
return m_Radius;
}
double Circle::computeDiameter()const{
return 2* m_Radius;
}
double Circle::computeArea()const {
return ( m_Radius* m_Radius*M_PI);
}
double Circle::computeCircumference()const {
return (2* m_Radius*M_PI);
}
#include <iostream>
#include <QTextStream>
#include "circle.h"
using namespace std;
int main(){
QTextStream cout(stdout);
Circle c1,c2; // input
c1.setRadius(3);
c2.setRadius(7);
cout << "Circle with radius " << c1.getRadius() << " has: " << endl;
cout<< "Diameter " << c1.computeDiameter() << " cm " <<endl;
cout<< "Area " << c1.computeArea() << " cm" <<endl;
cout<< "Circumference " << c1.computeCircumference()<< " cm " <<endl<<endl;
cout << "Circle with radius " << c2.getRadius() << " has: " << endl;
cout<< "Diameter " << c2.computeDiameter() << " cm " <<endl;
cout<< "Area " << c2.computeArea() << " cm" <<endl;
cout<< "Circumference " << c2.computeCircumference()<< " cm " <<endl<<endl;
return 0;
}
The function isBigger() returns true (or false) if the radius of the Circle instance on which the function is invoked is bigger (or smaller) than the radius of the Circle instance passed to the function.: I have no idea how to implement this function. Can someone explain this in simple english?
The implementation would look something like this:
bool Circle::isBiggerThan(const Circle& other) const
{
return m_Radius > other.m_Radius;
}
However, it is more idiomatic to use operators:
class Circle
{
// ...
friend bool operator >(Circle const &, Circle const &) const;
};
bool operator >(Circle const& lhs, Circle const& rhs) const
{
return lhs.m_Radius > rhs.m_Radius;
}
If you know your own radius (m_Radius or getRadius()) and the other circle's radius (other.getRadius()), then you can simply compare them to see which one has the bigger radius, like this:
bool Circle::isBigger(const Circle &other) const
{
return m_Radius > other.getRadius();
}
To make an example, if you have:
Circle c1;
Circle c2;
Then c1.isBigger(c2) should be true if and only if c1 has a greater radius than c2.
(I would probably have called the function isBiggerThan to make it easier to say aloud.)
Do you mean something like:
bool Circle::isBigger(const Circle& other) const
{
return m_Radius > other.getRadius();
}
This will simply check the current circle's radius (m_Radius) against the given circle's radius.
Related
My task is to practice inheritance, putting all the classes in separate files. I have a base class Circle and a derived class Cylinder.
What I'm stuck on is trying to display on the screen the result of my calculated area and volume for an object B of a Cylinder type. I found a way to do that for a Circle, though it doesn't work for my Cylinder.
circle.h
#pragma once
#include <iostream>
class Circle {
public:
float r;
Circle();
Circle(float r);
Circle circumference();
Circle area();
void view();
void getArea();
void getCircum();
};
circle.cpp
#include "circle.h"
#include <cmath>
using namespace std;
Circle::Circle() : r(5) {
cout << "Default constructor has been called for a circle\n";
}
Circle::Circle(float r) {
this->r = r;
cout << "Constructor with parameters has been called for a circle\n";
}
void Circle::view() {
cout << "Radius = " << r << endl;
}
Circle Circle::circumference() {
return 2 * M_PI * r;
}
Circle Circle::area() {
return M_PI * pow(r, 2);
}
void Circle::getArea() {
cout << "Area = " << r << " m^2";
}
void Circle::getCircum() {
cout << "Circumference = " << r << " m";
}
cylinder.h
#pragma once
#include <iostream>
#include "circle.h"
class Cylinder : public Circle {
public:
float h;
Cylinder();
Cylinder(float r, float h);
void view();
double area();
double volume(float r, float h);
void getArea();
void getVolume();
};
cylinder.cpp
#include "cylinder.h"
#include <cmath>
using namespace std;
Cylinder::Cylinder() : h(7) {
cout << "Default constructor has been called for a cylinder\n";
}
Cylinder::Cylinder(float r, float h) : Circle(r) {
this->h = h;
cout << "Constructor with parameters has been called fo a cylinder\n";
}
void Cylinder::view() {
Circle::view();
cout << "Height = " << h << endl;
}
double Cylinder::area() {
return 2 * M_PI * r * h;
}
double Cylinder::volume(float r, float h) {
return M_PI * pow(r, 2) * h;
}
void Cylinder::getArea() {
cout << "Area = " << h;
}
void Cylinder::getVolume() {
cout << "Volume = " << h;
}
main.cpp
#include <iostream>
#include "circle.h"
#include "cylinder.h"
using namespace std;
int main() {
Circle A;
A.view();
Circle A1(8);
A1.view();
Cylinder B;
B.view();
Cylinder B1(4, 6);
B1.view();
//A.area().getArea();
//cout << endl;
//A.circumference().getCircum();
//cout << endl;
//A1.area().getArea();
//cout << endl;
//A1.circumference().getCircum();
B.area().getArea();
return 0;
}
The error that I'm getting:
main.cpp: In function ‘int main()’:
main.cpp:26:14: error: request for member ‘getArea’ in ‘B.Cylinder::area()’, which is of non-class type ‘double’
26 | B.area().getArea();
| ^~~~~~~
I feel like neither my code in main() for instance B, nor my methods getArea() and getVolume() in class Cylinder, are correct. And there is probably a better approach to do the same for an object A and A1 of a Circle type, though the code I commented out actually works.
I know that this is a dumb question, and such things should be quite straightforward, but I am trying to learn and would be grateful for any advice on how I can fix this.
Well, the reason you are getting the error message:
main.cpp: In function ‘int main()’:
main.cpp:26:14: error: request for member ‘getArea’ in ‘B.Cylinder::area()’, which is of non-class type ‘double’
26 | B.area().getArea();
| ^~~~~~~
Is because you are basically doing this:
auto _ = B.area();
So here, _ deduces to be a double, and then you do:
_.getArea();
You are trying to access a member function from a double, and double doesn't have any member functions.
You probably meant to do this instead:
auto x = B.area();
B.h = x;
B.GetArea();
This assigns the area of B.area() to a variable x, and assigns x to B.h. B's member function then gets called and outputs the area.
In your getArea() function, instead of saying:
cout << "Area = " << endl;
Just say:
cout << "Area = " << area() << endl;
Then in your main.cpp, just call B.getArea().
Hope this helps!
I am trying to convert different coordinate systems. From polar to rectangular and vice versa. My pol_to_rect()function is not working properly. It is giving very small values(~10^(-44)) after converting and also before converting. There might be some problem while using the sin() and cos() functions. The rect_to_pol() is working fine for positive values.
Edit - When I changed atan() to atan2() how can I incorporate other values of x and y.
#include <iostream>
#include <cmath>
using namespace std;
#define PI 3.1415926
class Polar; // Forward declaration
class Rectangular {
private:
float x, y;
public:
Rectangular() {} // default constructor
Rectangular(float mv_x, float mv_y) {
x = mv_x;
y = mv_y;
}
void showData() const;
Polar rect_to_pol();
float& get_x() {
return x;
}
float& get_y() {
return y;
}
};
void Rectangular::showData() const {
cout << "--Rectangular--" << endl;
cout << "x: " << x << "\t" <<"y: " << y << endl;
}
class Polar {
private:
float r;
float theta;
public:
Polar() {} // default constructor
Polar(float mv_r, float mv_theta) {
r = mv_r;
theta = mv_theta;
}
void showData();
Rectangular pol_to_rect();
float& get_r(){
return r;
}
float& get_theta() {
return theta;
}
};
void Polar::showData() {
cout << "--Polar--" << endl;
cout << "r:" << r << "\t" << "Theta(Radians):" << theta << endl;
}
Rectangular Polar::pol_to_rect() {
Rectangular temp;
temp.get_x() = r * cos(theta*(PI/180.0)); // in degrees
temp.get_y() = r * sin(theta*(PI/180.0));
return temp;
}
Polar Rectangular::rect_to_pol() {
Polar temp;
temp.get_r() = sqrt(pow(x, 2) + pow(y, 2));
temp.get_theta() = atan2(y, x);
return temp;
}
int main()
{
Rectangular r1(-1, -1), r2;
Polar p1(12.0, 30.0), p2;
r1.showData();
p2 = r1.rect_to_pol();
cout << "After Conversion (RECT TO POLAR)->" << endl;
p2.showData();
p1.showData();
r2 = p1.pol_to_rect();
cout << "After Conversion (POLAR TO RECT)" << endl;
r2.showData();
return 0;
}
In my program I have created a constructor called Point with two values. I also have a set, get, scale and translate function. I'm trying to create a function that allows me to get the distance between the object and another point. I'm have trouble with it though any help would be brilliant.
#ifndef POINTMODEL
#define POINTMODEL
#define POINTDEB UG
#include <iostream>
#include <string.h>
using namespace std;
class Point {
public:
Point(void);
Point(double anX, double aY);
~Point();
void setPoint(double anX, double aY);
double getX();
double getY();
double scaleX(double theX);
double scaleY(double theY);
void translate(double theX, double theY);
void distance(const Point& aPoint);
protected:
private:
double theX;
double theY;
};
inline Point::Point(void)
{
theX = 1;
theY = 1;
cout << "\n The default constructor was called" << endl;
}
inline Point::Point(double anX, double aY)
{
cout << "\n regular constructor called";
}
inline Point::~Point()
{
cout << "\n the destructor was called" << endl;
}
inline void Point::setPoint(double anX, double aY)
{
theX = anX;
theY = aY;
}
inline double Point::getX()
{
return theX;
}
inline double Point::getY()
{
return theY;
}
inline double Point::scaleX(double theX)
{
return theX;
}
inline double Point::scaleY(double theY)
{
return theY;
}
inline void Point::translate(double offSetX, double offSetY)
{
cout << "X is translated by : " << offSetX << endl;
cout << "Y is translated by : " << offSetY << endl;
}
inline void Point::distance(const Point& aPoint)
{
}
#endif
Cpp file:
#include "Point.h"
using namespace std;
int main(void)
{
cout << "\n main has started" << endl;
//Point myPoint;
Point myPoint(1, 1);
myPoint.setPoint(1, 1);
cout << "\n The value for X is : " << myPoint.getX() << endl;
cout << "\n The value for Y is : " << myPoint.getY() << endl;
cout << "\n X scaled by 2 is : " << myPoint.scaleX(2) << endl;
cout << "\n Y scaled by 2 is : " << myPoint.scaleY(2) << endl;
myPoint.translate(2, 3);
cout << "\n main has finished" << endl;
return 0;
}
You need to make your Point::getX() and Point::getY() functions const like so:
inline double Point::getX() const
{
return theX;
}
If they are not const you cannot call them when the parameter is a const reference.
Then the distance is (changed return from void to double):
double distance(const Point & aPoint) const
{
const double x_diff = getX() - aPoint.getX();
const double y_diff = getY() - aPoint.getY();
return std::sqrt(x_diff * x_diff + y_diff * y_diff);
}
I have deliberately not used std::pow since the exponent is 2.
You also need to include <cmath> for std::sqrt.
Trying to get this homework figured out and I just keep hitting one wall after another. What I am getting now is the error message:
Error 1 error C2597: illegal reference to non-static member 'circleType::radius'
I have 2 header files, circleType.h and cylinderType.h and I need to out put results for shipping and painting costs that a user would enter. A little help before I go completely out of my mind ... Thank you.
circle.h
class circleType
{
public:
static void setRadius(double r);
double getRadius();
double area();
double circumference();
circleType(double r = 0);
private:
double radius;
};
void circleType::setRadius(double r)
{
if (r >= 0)
{
radius = r;
}
else
{
radius = 0;
}
}
double circleType::getRadius()
{
return radius;
}
double circleType::area()
{
return 3.1416 * radius * radius;
}
double circleType::circumference()
{
return 2 * 3.1416 * radius;
}
circleType::circleType(double r)
{
setRadius(r);
}
cylinderTyper.h
#include "circleType.h"
class cylinderType: public circleType
{
public:
static void setRadius(double r);
static double getRadius();
static double area();
static double circumference();
cylinderType(double r = 0);
private:
double radius;
};
main.cpp
#include "stdafx.h"
#include "cylinderType.h"
#include <iostream>
#include <iomanip>
#include <string>
using namespace std;
void enterData(int& cylinderBase,int& cylinerHeight, double& shipCost, double& paintCost);
int main()
{
cout << fixed << showpoint << setprecision(2);
int cylinderBase, cylinderHeight;
double sCost, pCost, shipCost, paintCost, volume, area = 0, circumference = 0;
enterData(cylinderBase, cylinderHeight, shipCost, paintCost);
cylinderType::setRadius(cylinderBase + cylinderHeight);
cylinderType::getRadius();
cylinderType::area();
cylinderType::circumference();
cout << "Cost of shipping: $" << circumference * shipCost << endl;
cout << "Cost of painting: $" << area * paintCost << endl;
system("pause");
return 0;
}
void enterData(int& cylinderBase, int& cylinderHeight, double& shipCost, double& paintCost)
{
cout << "Enter the base size of cylinder: ";
cin >> cylinderBase;
cout << endl;
cout << "Enter the hight size of cylinder: ";
cin >> cylinderHeight;
cout << endl;
cout << "Enter shipping cost per liter: ";
cin >> shipCost;
cout << endl;
cout << "Enter cost of painting per square foot: ";
cin >> paintCost;
cout << endl;
}
It's a very simple rule: static member functions can only access member variables that are static as well. That's because a static function isn't called against a specific object, so object members don't make sense in that context.
In your case, the static function setRadius is trying to modify the member variable radius which is not static. I suspect that you really don't want setRadius to be a static function.
This question already has answers here:
What is an undefined reference/unresolved external symbol error and how do I fix it?
(39 answers)
Closed 9 years ago.
So far I've managed to fix my own errors, but this one is keeping me puzzled for a while now. If any of you have any hints, that would be greately appreciated! Thanks.
I'm using Eclipse on a Windows laptop, which gives me the following error after building:
undefined reference to `Point::Point()' circle.cpp
/Assignment4_1/IN4084MSc line 13 C/C++ Problem
All my files (main4_1.cpp, point.h, point.cpp, circle.h, circle.cpp) are part of a project (called Assignment4_1).
#include "point.h"
#include "circle.h"
#include <cmath>
using namespace std;
Circle::Circle(Point ct, double rd):Point(ct)
{
center = ct;
if(rd > 0)
{
radius = rd;
}
radius = -1;
}
Point Circle::get_center(){
return center;
}
double Circle::get_radius(){
return radius;
}
void Circle::print(){
cout << " <Circle(<Point(“"<<center.get_x()<<"”,“"<<center.get_y()<<"”)>,”"<<radius<<"”)>";
}
void Circle::print(string s){
cout << s;
print();
}
void Circle::println(){
print();
cout << endl;
}
void Circle::println(string s){
print(s);
cout << endl;
}
#ifndef CIRCLE_H_
#define CIRCLE_H_
#include <iostream>
#include "point.h"
using namespace std;
class Circle: public Point{
Point center;
double radius;
public:
Circle(Point ct, double rd);
Point get_center();
double get_radius();
void print();
void print(string s);
void println();
void println(string s);
};
#endif /* CIRCLE_H_ */
#include "point.h"
#include <cmath>
using namespace std;
Point::Point(double x, double y){
x_coord = x;
y_coord = y;
}
double Point::get_x(){
return x_coord;
}
double Point::get_y(){
return y_coord;
}
void Point::print(){
//post: has printed the contents of the Point object in the format
cout << "<Point( “ " << x_coord <<" ” , “ " << y_coord << " ” )>";
}
void Point::print(string s){
//post: has printed string s first, then printed the contents of the Point object
cout << s << " ";
print();
}
void Point::println(){
//post: has printed the contents of Point object, then moved the cursor to the next line
print();
cout << endl;
}
void Point::println(string s){
//post: has printed string s first, then printed the contents of the Point object, and moved the cursor to the next line
cout << s << " ";
println();
}
void Point::move(double dx, double dy){
// post: x_coord = x_coord + dx, y_coord = y_coord + dy
x_coord = x_coord + dx;
y_coord = y_coord + dy;
}
double Point::distance(Point that){
//post: returns the distance between this Point and that Point
return sqrt( pow(x_coord - that.get_x(),2) + pow(y_coord - that.get_y(),2) );
}
bool Point::equals(Point that){
//post : returns true if this Point and that Point have the same coordinates
return (x_coord = that.get_x());
}
#ifndef POINT_H_
#define POINT_H_
#include <iostream>
using namespace std;
class Point{
protected:
double x_coord;
double y_coord;
public:
Point(double x, double y);
Point();
double get_x();
double get_y();
void print();
void print(string s);
void println();
void println(string s);
void move(double dx, double dy);
double distance(Point that);
bool equals(Point that);
};
#endif /* POINT_H_ */
#include <iostream>
#include <cstdlib>
using namespace std;
#include "point.h"
#include "circle.h"
void test1(){
cout << "test1:" << endl;
Point p1 = Point(2,3);
cout << "Point p1 is created, the data of p1 = (2,3)" << endl;
cout << "p1.get_x() -> " << p1.get_x() << endl;
cout << "p1.get_y() -> " << p1.get_y() << endl << endl;
p1.println("p1.println() -> ");
cout << endl;
cout << "end test1" << endl << endl;
}
void test2(){
cout << "test2:" << endl;
cout << "Point p1 is created, the data of p1 = (2,3)" << endl;
cout << "Point p2 is created, the data of p2 = (0,0)" << endl;
Point p1 = Point(2,3);p1.println("p1.println() -> ");
Point p2 = Point(0,0);p2.println("p2.println() -> ");
cout << endl;
p1.println("p1 before move -> ");
cout << "p1.move(1,1)" << endl;p1.move(1,1);
p1.println("p1 after move -> ");
cout << endl;
cout << "p1.distance(p2) -> " << p1.distance(p2) << endl << endl;
cout << "p1.equals(p1) -> " << p1.equals(p1) << endl;
cout << "p1.equals(p2) -> " << p1.equals(p2) << endl;
cout << "end test2" << endl << endl;
}
int main(){
test1();
test2();
return 0;
}
The compiler is telling you to define
Point::Point()
which you have only declared in the Point class definition. A possible implementation would be to initialize both coordinates with 0.0:
Point::Point() : x_coord(0.0), y_coord(0.0) {}
You have to explicitly initialize the members in this case because built-in types do not get zero-initialized when default constructed.