19.属性(2)

get获取属性值 set设置属性值

 

namespace _19.属性_2_
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            User zs = new User();
            zs.Birthday = Convert.ToDateTime("1999-1-1");
            MessageBox.Show("年龄：" + zs.Age);

        }
    }
    class User
    {
        private DateTime m_Birthday;
        public DateTime Birthday//只写属性
        {
            set                
            {
                if (value < Convert.ToDateTime("1900-1-1") || value.Year > DateTime.Now.Year-3)
                    MessageBox.Show("wrong!");
                else 
                m_Birthday =value ;
            }
        }
        public int Age//只读属性
        {
            get
            {
                return DateTime.Now.Year - m_Birthday.Year;
            }
        }
    }
}

在类里面声明一个计数器，用来记录网站被访问的次数（显示“4”）

namespace _19.属性_2_
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            User zs = new User();
            User w1 = new User();
            User w2 = new User();
            User e3 = new User();
            MessageBox.Show(User.LoginCount+"");

        }
    }
    class User
    {
        private static int m_LoginCount;
        public User()
        {
            m_LoginCount++;
        }
        public static int LoginCount //静态只读属性
        {
            get
            {
                return m_LoginCount;
            }
        }
   }
}