Class Type Redefinition C++

Question

I have seen other people asking this question before, but the answers they received were unique to their programs and unfortunately do not help me.

Firstly, I have a shape class - split into .h and .cpp files

//Shape.h

    #include <string>
using namespace std;

class Shape
{
private:
    string mColor;

public:
    Shape(const string& color); // constructor that sets the color instance value
    string getColor() const; // a const member function that returns the obj's color val
    virtual double area() const = 0;
    virtual string toString() const = 0;
};

//Shape.cpp

#include "Shape.h"
using namespace std;

Shape::Shape(const string& color) : mColor(NULL) {
    mColor = color;
}
string Shape::getColor() const
{
    return mColor;
}

I keep getting an error in my Shape.h class that says 'Shape' : 'class' type redefinition. Any idea why I might be getting this error?

Answer 1

add include guard to your header file

#ifndef SHAPE_H
#define SHAPE_H

// put your class declaration here

#endif

And the way you initialize member mColor is incorrect. You can't assign NULL to string type

Shape::Shape(const string& color) : mColor(color) {
}

Add virtual destructor to Shape class as it serves as a base with virtual functions.

Also, do NOT use using directive in header file.

Answer 2

It seems like you want to write an abstract base class here, but is there any other files you compiled but not showed here?

---

You must include “shape.h” twice more. Just use macros to prevent this case.

PS：I guess Rectangle is base class of Square,and also inherited Shape.