属性，构造函数的基本应用

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Test2
{
    class Ticket
    {
        decimal distance;

        public decimal Price
        {
            get 
            {
                if (distance > 0 && distance < 10)
                    return 1.0m * distance;
                else if (distance >= 10 && distance < 20)
                    return 0.9m * distance;
                else
                    return 0.8m * distance;
            }
        }

        public decimal Distance
        {
            get { return distance; }
            set 
            { 
                if(distance <0)
                {
                    throw new Exception("距离不能为负数");
                }
               
                distance = value;
            }
        }

        public void ShowPrice()
        {
            Console.WriteLine("距离：{0}  票价：{1}", distance, Price);
        }

        public Ticket(decimal distance)
        {
            this.distance = distance;
        }
        public Ticket()
        {

        }
    }
}

　　

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Test2
{
    class Program
    {
        static void Main(string[] args)
        {
            Ticket t1 = new Ticket(9);
            t1.ShowPrice();

            Ticket t2 = new Ticket();
            t2.Distance = 10;

            t2.ShowPrice();

            Console.ReadKey();

        }
    }
}