Design patterns 工厂模式输出示例未显示

我试图实现GoF工厂模式，但由于某些原因，我没有得到输出

下面的所有文件都是用-std=gnu++14参数编译的

下面是一个

shape.h

头文件，我在其中定义了一个（抽象）类

shape

class Shape
{
    public:
        virtual void draw() {}
};

现在我有了另一个头文件

shapes.h

，其中我编写了三个扩展

Shape

类的具体类。我还重写了每个类中的

draw（）

#include "shape.h"
#include <iostream>

using std::cout;

class Circle : public Shape
{
    public:
        void draw()
        {
            cout << "Inside Circle::draw()\n";
        }
};

class Square : public Shape
{
    public:
        void draw()
        {
            cout << "Inside Square::draw()\n";
        }
};

class Rectangle : public Shape
{
    public:
        void draw()
        {
            cout << "Inside Rectangle::draw()\n";
        }
};

最后是我们的驱动程序：

#include "shapefactory.h"

int main()
{
    Shapefactory shapeFactory;
    Shape shape1 = shapeFactory.get_shape("CIRCLE");
    shape1.draw();

    Shape shape2 = shapeFactory.get_shape("RECTANGLE");
    shape2.draw();

    Shape shape3 = shapeFactory.get_shape("SQUARE");
    shape3.draw();

    return 0;
}

---

形状的

draw（）

均未提供输出。我哪里出错了？

通过将get\u shape（）的返回类型更改为shape来修复*

Shape* get_shape(string shape)
    {
        if (iequals(shape , "CIRCLE"))
            return new Circle();
        else if (iequals(shape , "SQUARE"))
            return new Square();
        else if (iequals(shape , "RECTANGLE"))
            return new Rectangle();
        else
            return NULL;
    }

同样，我还必须修改驱动程序

int main()
{
    Shapefactory shapeFactory;
    Shape *shape1 = shapeFactory.get_shape("CIRCLE");
    (*shape1).draw();

    Shape *shape2 = shapeFactory.get_shape("RECTANGLE");
    (*shape2).draw();

    Shape *shape3 = shapeFactory.get_shape("SQUARE");
    (*shape3).draw();

    return 0;
}

int main()
{
    Shapefactory shapeFactory;
    Shape *shape1 = shapeFactory.get_shape("CIRCLE");
    (*shape1).draw();

    Shape *shape2 = shapeFactory.get_shape("RECTANGLE");
    (*shape2).draw();

    Shape *shape3 = shapeFactory.get_shape("SQUARE");
    (*shape3).draw();

    return 0;
}