c++ - 当重载大于运算符以比较来自不同类的两个 double 值时，出现操作数错误

Question

我正在做家庭作业:

1. 使用重载 + 添加 2 个圆的面积

2. 使用重载 + 添加 2 个矩形的面积

3. 使用重载比较圆形和矩形的面积是否相同 ==

4. 使用重载比较圆形和矩形的面积，看哪个更大 >

到目前为止，我已经完成了前三个。我已经为大于函数重载编写了代码，但我一直收到错误消息——“没有运算符”>“匹配这些操作数”

我已经尝试将运算符函数更改为类 rectangle 和类 circle 的成员函数。我什至尝试将 > 运算符更改为其他运算符，但我仍然遇到相同的错误。

ShapesType.h选择-

    friend bool operator==(const circleType&,
    const rectangleType&);
//Overload the operator ==

    friend bool operator>(const circleType&,
    const rectangleType&);
//Overload the operator >

ShapesTypeImp.cpp 选择-

    bool operator== (const circleType& Circle,
    const rectangleType& rectangle)
    {
          return Circle.area() == rectangle.area();
    }

    bool operator> (const circleType& Circle,
    const rectangleType& rectangle)
    {
          return (Circle.area() > rectangle.area());
    }

Main.cpp选择-

                case 3:
            cout << "Enter the radius of the circle: ";
            cin >> radius;

            while (cin.fail())
            {
                cin.clear();
                cin.ignore(100, '\n');
                cout << endl << "Not a valid input, enter a number: ";
                cin >> radius;
            }

            cout << "Enter the height of the rectangle: ";
            cin >> height;

            while (cin.fail())
            {
                cin.clear();
                cin.ignore(100,'\n');
                cout << endl << "Not a valid input, enter a number: ";
                cin >> height;
            }

            cout << "Enter the width of the rectangle: ";
            cin >> width;

            while (cin.fail())
            {
                cin.clear();
                cin.ignore(100,'\n');
                cout << endl << "Not a valid input, enter a number: ";
                cin >> width;
            }

            circle.setRadius(radius);
            rectangle.setDimensions(height, width);
            cout << "The area of the circle is: " << circle.area() << endl;
            cout << "The area of the rectangle is: " << rectangle.area() << endl;
            if (circle == rectangle)
            {
                cout << "The area of the circle is equal to the area of the rectangle.";
            }
            else
                cout << "The area of the circle is not equal to the area of the rectangle.";

            cout << endl << endl;
            break;

        case 4:
            cout << "Enter the radius of the circle: ";
            cin >> radius;

            while (cin.fail())
            {
                cin.clear();
                cin.ignore(100, '\n');
                cout << endl << "Not a valid input, enter a number: ";
                cin >> radius;
            }

            cout << "Enter the height of the rectangle: ";
            cin >> height;

            while (cin.fail())
            {
                cin.clear();
                cin.ignore(100, '\n');
                cout << endl << "Not a valid input, enter a number: ";
                cin >> height;
            }

            cout << "Enter the width of the rectangle: ";
            cin >> width;

            while (cin.fail())
            {
                cin.clear();
                cin.ignore(100, '\n');
                cout << endl << "Not a valid input, enter a number: ";
                cin >> width;
            }

            circle.setRadius(radius);
            rectangle.setDimensions(height, width);
            cout << "The area of the circle is: " << circle.area() << endl;
            cout << "The area of the rectangle is: " << rectangle.area() << endl;
            if (circle > rectangle)
            {
                cout << "The area of the circle is greater than the area of the rectangle.";
            }
            else
                cout << "The area of the rectangle is greater than the circle.";

            cout << endl << endl;
            break;

我将案例 3 包括在内，因为它按预期工作。案例 4，使用几乎相同的代码，给出了一个操作数错误。似乎它正在尝试使用 std > 而不是重载的 >。我不确定如何解决此问题，我们将不胜感激任何帮助或见解。

附件是错误的图片:

Answer 1

我试图得到错误，然而这个小例子是有效的cpp.sh/8excr

也许你应该给 area 函数添​​加 const 限定符