UML—里氏替换原则

例子：

测试代码：

#include <iostream>

using namespace std;

//书类Book
class Book
{
private:
    int width;
    int height;
public:
    virtual void madeByWood()
    {
        cout<<"I'm made by wood!";
    }
    virtual void setI(int w,int h)
    {
        width=w;
        height=h;
    }
    virtual int getW()
    {
        return width;
    }
    virtual int getH()
    {
        return height;
    }
};

//电子书类E_book
class E_book:public Book
{
public:
    void madeByWood()
    {
        cout<<"I'm not made by wood!";
    }
    void setI(int w,int h)
    {
        Book::setI(0,0);
    }
    int getW()
    {
        return Book::getW();
    }
    int getH()
    {
        return Book::getH();
    }
};

//测试类TextBook
class TextBook
{
public:
    void caleArea(Book &book)
    {
        try
        {
            if(book.getW()==0&&book.getH()==0)
                throw 0;
            int area=book.getW()*book.getH();
            cout<<"书的面积为："<<area<<endl;
        }
        catch(int)
        {
            cout<<"An error occured!"<<endl;
        }
    }
};

int main()
{
    Book b;
    b.setI(8,12);
    E_book e;
    e.setI(0,0);
    TextBook t;
    t.caleArea(b);
    t.caleArea(e);
    return 0;
}

运行结果：

里氏替换原则：

（编辑：李大同）

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