1、里氏转换
1)、子类可以赋值给父类
2)、如果父类中装的是子类对象,那么可以将这个父类强转为子类对象。
子类对象可以调用父类中的成员,但是父类对象永远都只能调用自己的成员。
class Program
{
static void Main(string[] args)
{
//Person p = new Teacher();//子类可以赋值给父类
//Teacher t = (Teacher)p;//如果父类里面装的是子类对象,可以将父类强转为子类
//t.TeacherSayHello();
//Console.ReadKey();
Person p = new Teacher();
if (p is Teacher)
{
Teacher t = (Teacher)p;
t.TeacherSayHello();
}
else
{
Console.WriteLine("转换失败");
}
Console.ReadKey();
//Person p = new Teacher();
//Teacher t = p as Teacher;//能够转换,返回对应的对象
//(p as Student).StudentSayHello();//不能转换,返回null
//t.TeacherSayHello();
//Console.ReadKey();
}
}
public class Person
{
private string _name;
public string Name
{
get { return _name; }
set { _name = value; }
}
private char _gender;
public char Gender
{
get { return _gender; }
set { _gender = value; }
}
private int _age;
public int Age
{
get { return _age; }
set { _age = value; }
}
public void SayHello()
{
Console.WriteLine("我是人类");
}
}
public class Teacher : Person
{
private decimal _salary;
public decimal Salary
{
get { return _salary; }
set { _salary = value; }
}
public void TeacherSayHello()
{
Console.WriteLine("我是一名教师");
}
}
public class Student:Person
{
private string _id ;
public string Id
{
get { return _id; }
set { _id = value; }
}
public void StudentSayHello()
{
Console.WriteLine("我是学生");
}
}
2、is和as
is:表示类型转换,如果能够转换成功,则返回一个true,否则返回一个false
as:表示类型转换,如果能够转换则返回对应的对象,否则返回一个null