第五讲-面向对象编程(二)继承封装和多态.ppt

第五讲面向对象编程(二)继承、封装和多态4.3继承、封装和多态4.3.1类的继承1.派生子类2.域的继承、添加与隐藏3.方法的继承、添加与覆盖方法重载举例方法隐藏举例虚方法覆盖举例4.3.2类的封装publicclassStudent
{privatestringstudentname;
publicstringgetstudentname()
{return(studentname)；}
publicstringsetstudentname(stringna)
{studentname=na;}
}
4.3.3多态虚方法重写举例：定义基类圆形Round，有一个成员半径，编写构造函数和计算面积的虚方法Area（）;再定义一个派生类球形Sphere,对虚方法Area进行重写。1.this关键字this关键字举例this的注意事项2.base关键字：base指的是父类base（用法2）举例4.4运算符重载4.4.1多态之二：运算符的重载usingSystem;
Classclass1
{publicintx1,x2;
publicclass1()
{x1=1;x2=2;}
publicstaticintoperator++(class1c)
{c.x1=c.x1+10;
c.x2=c.x2+5;}
PublicvoidShow()
{Console.WriteLine(“{0},{1}”,x1,x2);}
}usingSystem;
Classclass1
{publicintx1,x2;
publicclass1()
{x1=1;x2=2;}
publicstaticclass1operator+(class1c1,class1c2)
{c1.x1=c1.x1+c2.x1;
c1.x2=c1.x2+c2.x2;
return(c1);}
PublicvoidShow()
{Console.WriteLine(“{0},{1}”,x1,x2);}
}