纯c语言实现面向对象分析与示例分享

/*  父类  */
struct  parent_class
{
  int  a,  b;
  char  *str;
};

/*  继承于父类的子类  */
struct  child_class
{
  struct  parent class  p;
  int  a,  b;
};

/*  操作示例函数*/
void  func()
{
  struct  child_class  obj,  *obj_ptr;  /*  子类对象及指针  */
  struct  parent_class  *parent_ptr;  /*  父类指针  */
  obj_ptr  =  &obj;

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

  /*  可通过转换过类型的父类指针访问相应的属性  */
  parent ptr->a  =  1;
  parent ptr->b  =  5;

  /*  子类属性的操作  */
  obj ptr->a  =  10;
  obj ptr->b  =  100;
}

/*  抽象父类  */
struct  parent_class
{
  int  a;

  /*  反映不同类别属性的方法  */
  void  (*vfunc)(int  a);
}

/*  抽象类的方法调用  */
void  parent_class_vfunc(struct  parent_class  *self,  int  a)
{
  assert(self  !=  NULL);
  assert(slef->vfunc  !=  NULL);

  /*  调用对象本身的虚拟函数  */
  self->vfunc(a);
}

/*  继承自parent class的子类  */
struct  child_class
{
  struct  parent_class  parent;
  int  b;
};

/*  子类的构造函数  */
void  child_class_init(struct  child_class*  self)
{
  struct  parent_class*  parent;

  /*  强制类型转换获得父类指针  */
  parent  =  (struct  base_class*)  self;
  assert(parent  !=  NULL);

  /*  设置子类的虚拟函数  */
  parent->vfunc  =  child_class_vfunc;
}

/*  子类的虚拟函数实现  */
static  void   child class vfunc(struct  child class*self,  int  a)
{
  self->b  =  a  +  10;
}

#include <stdio.h>
#include <stdlib.h>

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

//类
#ifndef Class
#define Class struct
#endif

//抽象形状类
Class Shape;
typedef Class Shape shape;
//抽象形状类的方法声明
shape* Shape(int edges);
int shape_getEdges(shape *);
int shape_getArea(void);
void _Shape(shape *);

//三角形类
Class Triangle;
typedef Class Triangle triangle;
//三角形类的方法声明
triangle * Triangle(int bottom, int height);
int triangle_getEdges(triangle *);
int triangle_getArea(triangle *);
void _Triangle(triangle *);

//矩形类
Class Rectangle;
typedef Class Rectangle rectangle;
//矩形类的方法声明
rectangle * Rectangle(int bottom, int height);
int rectangle_getEdges(rectangle *);
int rectangle_getArea(rectangle *);
void _Rectangle(rectangle *);

//抽象形状类实现
Class Shape
{
    int edges;
    int (*getEdges)(shape*);
    int (*getArea)(void);
};

//形状类构造函数
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;
}

//形状类析构函数
void _Shape(shape * obj)
{
    if(obj == NULL)
        return;
    free(obj);
}

//三角形类实现
Class Triangle
{
    shape * super;
    int bottom;
    int height;
    int (*getEdges)(triangle *);
    int (*getArea)(triangle *);
};

//三角形类构造函数
triangle * Triangle(int bottom, int height)
{
    triangle* obj = (triangle*) malloc(sizeof(triangle));
    //调用Shape构造函数用于实现继承
    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;
}

//三角形类析构函数
void _Triangle(triangle * triangle)
{
    _Shape(triangle->super);

    if(triangle == NULL)
    {
        return;
    }

    free(triangle);
}

//矩形类实现
Class Rectangle
{
    shape * super;
    int bottom;
    int height;
    int (*getEdges)(rectangle *);
    int (*getArea)(rectangle *);
};

//矩形类构造函数
rectangle * Rectangle(int bottom, int height)
{
    rectangle * obj = (rectangle *)malloc(sizeof(rectangle));
    //调用Shape构造函数用于实现继承
    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);
}

//矩形类析构函数
void _Rectangle(rectangle * obj)
{
    _Shape(obj->super);
    if(obj == NULL)
    {
        return;
    }
    free(obj);
}

//测试
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);
}