c ++ création d'objet à l'intérieur de la classe - Stack Overflow

I have created 2 classes.One is called Shape and its a virtual class.The other one is called Circle(I intend to create more of them like : triangle,square ....).I want to find circle area of the object,but that isnt important.Here is my problem.When I want to create an object like this :

vector<Shape *> mStack;
Shape *newShape = NULL;
newShape = new Circle(10.6);
mStack.push_back(newShape);

I can create it in the main file without problems.But when I try to create a function of it inside the "Shape" class..like this:

void Shape::Create()
{
    Shape *newShape = NULL;
    newShape = new Circle(10.6);
    mStack.push_back(newShape);
}

I get following error: syntax error: identifier 'Circle'

... Here are my classes.

#pragma once
#include <vector>

using namespace std;

class Shape
{

private:
    vector<Shape *> mStack;
public:
    Shape();
    ~Shape(void);

    virtual double Circle_area() = 0;   


};


*********************************************************

#pragma once
#include "Shape.h"

class Circle : public Shape
{
private:
    double m_r;
public:
    Circle();
    Circle(double r);
    ~Circle(void);

    double Create();
    double Circle_area();
};

Where is the problem here? How can I create an object inside the parent class? I hope you understand what I am trying to say. Thanks for the help.

Your Design is now improper. By proper design, your shape could act as an abstract class or base class for the real circles or rectangles. If then your design will be.,

And in main() you could maintain, a list of shapes vector<Shape *> mStack; which will not create problem. But you must not create circle or rectangle in shape. Thats a wrong design in my point of view.

Your base class is more than weird.

• a base class should have virtual destructor


• having a collection of itself is suspect for overreaching (you might have a CompositeShape down the hierarchy...)


• It has a function named as a subclass. (could be shape_area() or just area())

Your implementation trouble is coming from this too: if the collection is not in shape, then create would not want to fill it, and problem gone.

From the provided info it's not clear where the content of create should go, may be the app, or may be some specific complex shape -- those could simply include all the required headers.

I have created 2 classes.One is called Shape and its a virtual class.The other one is called Circle(I intend to create more of them like : triangle,square ....).I want to find circle area of the object,but that isnt important.Here is my problem.When I want to create an object like this :

vector<Shape *> mStack;
Shape *newShape = NULL;
newShape = new Circle(10.6);
mStack.push_back(newShape);

I can create it in the main file without problems.But when I try to create a function of it inside the "Shape" class..like this:

void Shape::Create()
{
    Shape *newShape = NULL;
    newShape = new Circle(10.6);
    mStack.push_back(newShape);
}

I get following error: syntax error: identifier 'Circle'

... Here are my classes.

#pragma once
#include <vector>

using namespace std;

class Shape
{

private:
    vector<Shape *> mStack;
public:
    Shape();
    ~Shape(void);

    virtual double Circle_area() = 0;   


};


*********************************************************

#pragma once
#include "Shape.h"

class Circle : public Shape
{
private:
    double m_r;
public:
    Circle();
    Circle(double r);
    ~Circle(void);

    double Create();
    double Circle_area();
};

Where is the problem here? How can I create an object inside the parent class? I hope you understand what I am trying to say. Thanks for the help.

Your Design is now improper. By proper design, your shape could act as an abstract class or base class for the real circles or rectangles. If then your design will be.,

And in main() you could maintain, a list of shapes vector<Shape *> mStack; which will not create problem. But you must not create circle or rectangle in shape. Thats a wrong design in my point of view.

Your base class is more than weird.

• a base class should have virtual destructor


• having a collection of itself is suspect for overreaching (you might have a CompositeShape down the hierarchy...)


• It has a function named as a subclass. (could be shape_area() or just area())

Your implementation trouble is coming from this too: if the collection is not in shape, then create would not want to fill it, and problem gone.

From the provided info it's not clear where the content of create should go, may be the app, or may be some specific complex shape -- those could simply include all the required headers.

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