样本工厂模式输出未显示

下面的所有文件都是用-std=gnu++14参数编译的。

下面是 shape.h Shape

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

现在我有了另一个头文件 shapes.h 我写了三个具体的类来扩展 形状 上课。我也超越了 draw() 在每个班级里。

#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";
        }
};

现在我有一个 Shapefactory shapefactory.h 那会给我一个 形状

#include "shapes.h"
#include <string>
#include <algorithm>

using std::string;

class Shapefactory
{
    private:
        bool iequals(const string& a, const string& b)
        {
            return std::equal
                (a.begin(), a.end(),
                b.begin(), b.end(),
                [](char a, char b) {
                    return tolower(a) == tolower(b);
                }
            );
        }
    public:
        Shape get_shape(string shape)
        {
            if (iequals(shape , "CIRCLE"))
                return Circle();
            else if (iequals(shape , "SQUARE"))
                return Square();
            else if (iequals(shape , "RECTANGLE"))
                return Rectangle();
            else
                return Circle();
        }
};

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;
}

没有一个形状是 绘制()