/*  繼承于父類的子類  */
struct  child_class
{
  struct  parent class  p;
  int  a,  b;
};

/*  操作示例函數(shù)*/
void  func()
{
  struct  child_class  obj,  *obj_ptr;  /*  子類對象及指針  */
  struct  parent_class  *parent_ptr;  /*  父類指針  */
  obj_ptr  =  &obj;

  /*  取父指針  */
  parent_ptr  =  (struct  parent*)  &obj;

  /*  可通過轉(zhuǎn)換過類型的父類指針訪問相應(yīng)的屬性  */
  parent ptr->a  =  1;
  parent ptr->b  =  5;

  /*  子類屬性的操作  */
  obj ptr->a  =  10;
  obj ptr->b  =  100;
}

  /*  反映不同類別屬性的方法  */
  void  (*vfunc)(int  a);
}

/*  抽象類的方法調(diào)用  */
void  parent_class_vfunc(struct  parent_class  *self,  int  a)
{
  assert(self  !=  NULL);
  assert(slef->vfunc  !=  NULL);

  /*  調(diào)用對象本身的虛擬函數(shù)  */
  self->vfunc(a);
}

/*  繼承自parent class的子類  */
struct  child_class
{
  struct  parent_class  parent;
  int  b;
};

/*  子類的構(gòu)造函數(shù)  */
void  child_class_init(struct  child_class*  self)
{
  struct  parent_class*  parent;

  /*  強制類型轉(zhuǎn)換獲得父類指針  */
  parent  =  (struct  base_class*)  self;
  assert(parent  !=  NULL);

  /*  設(shè)置子類的虛擬函數(shù)  */
  parent->vfunc  =  child_class_vfunc;
}

/*  子類的虛擬函數(shù)實現(xiàn)  */
static  void   child class vfunc(struct  child class*self,  int  a)
{
  self->b  =  a  +  10;
}

//接口
#ifndef Interface
#define Interface struct
#endif

//類
#ifndef Class
#define Class struct
#endif

//抽象形狀類
Class Shape;
typedef Class Shape shape;
//抽象形狀類的方法聲明
shape* Shape(int edges);
int shape_getEdges(shape *);
int shape_getArea(void);
void _Shape(shape *);

//三角形類
Class Triangle;
typedef Class Triangle triangle;
//三角形類的方法聲明
triangle * Triangle(int bottom, int height);
int triangle_getEdges(triangle *);
int triangle_getArea(triangle *);
void _Triangle(triangle *);

//矩形類
Class Rectangle;
typedef Class Rectangle rectangle;
//矩形類的方法聲明
rectangle * Rectangle(int bottom, int height);
int rectangle_getEdges(rectangle *);
int rectangle_getArea(rectangle *);
void _Rectangle(rectangle *);

//抽象形狀類實現(xiàn)
Class Shape
{
    int edges;
    int (*getEdges)(shape*);
    int (*getArea)(void);
};

//形狀類構(gòu)造函數(shù)
shape* Shape(int edges)
{
    shape * obj = (shape *) malloc(sizeof(shape));
    obj->edges = edges;
    obj->getEdges = shape_getEdges;
    obj->getArea = shape_getArea;
    return obj;
}

int shape_getEdges(shape* obj)
{
    return obj->edges;
}

int shape_getArea(void)
{
    return -1;
}

//形狀類析構(gòu)函數(shù)
void _Shape(shape * obj)
{
    if(obj == NULL)
        return;
    free(obj);
}

//三角形類實現(xiàn)
Class Triangle
{
    shape * super;
    int bottom;
    int height;
    int (*getEdges)(triangle *);
    int (*getArea)(triangle *);
};

//三角形類構(gòu)造函數(shù)
triangle * Triangle(int bottom, int height)
{
    triangle* obj = (triangle*) malloc(sizeof(triangle));
    //調(diào)用Shape構(gòu)造函數(shù)用于實現(xiàn)繼承
    obj->super = Shape(3);
    obj->bottom = bottom;
    obj->height = height;
    obj->getEdges = triangle_getEdges;
    obj->getArea = triangle_getArea;
    return obj;
}

int triangle_getEdges(triangle * obj)
{
    return obj->super->edges;
}

int triangle_getArea(triangle * obj)
{
    return (obj->bottom * obj->height) / 2;
}

//三角形類析構(gòu)函數(shù)
void _Triangle(triangle * triangle)
{
    _Shape(triangle->super);

    if(triangle == NULL)
    {
        return;
    }

    free(triangle);
}

//矩形類實現(xiàn)
Class Rectangle
{
    shape * super;
    int bottom;
    int height;
    int (*getEdges)(rectangle *);
    int (*getArea)(rectangle *);
};

//矩形類構(gòu)造函數(shù)
rectangle * Rectangle(int bottom, int height)
{
    rectangle * obj = (rectangle *)malloc(sizeof(rectangle));
    //調(diào)用Shape構(gòu)造函數(shù)用于實現(xiàn)繼承
    obj->super = Shape(4);
    obj->bottom = bottom;
    obj->height = height;
    obj->getEdges = rectangle_getEdges;
    obj->getArea = rectangle_getArea;
    return obj;
}

int rectangle_getEdges(rectangle * obj)
{
    return obj->super->edges;
}

int rectangle_getArea(rectangle * obj)
{
    return (obj->bottom * obj->height);
}

//矩形類析構(gòu)函數(shù)
void _Rectangle(rectangle * obj)
{
    _Shape(obj->super);
    if(obj == NULL)
    {
        return;
    }
    free(obj);
}

//測試
void main(){
    shape* shapeObj = Shape(0);
     printf("%d\n", shapeObj->getEdges(shapeObj));
    printf("%d\n", shapeObj->getArea());
    _Shape(shapeObj);

    triangle* triangleObj = Triangle(4, 5);
    printf("%d\n", triangleObj->getEdges(triangleObj));
    printf("%d\n", triangleObj->getArea(triangleObj));
    _Triangle(triangleObj);

    rectangle* rectangleObj = Rectangle(4, 5);
    printf("%d\n", rectangleObj->getEdges(rectangleObj));
    printf("%d\n", rectangleObj->getArea(rectangleObj));
    _Rectangle(rectangleObj);
}