接口的例子

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

namespace ConsoleApplication1
{
    public interface IPrints
    {
        double a { set; }
        void Print();
        void PrintPreview();
    }
    public class IPrint
    {
        static void Main()
        {
            Console.WriteLine("Plesas select printer：");
            string printerName = Console.ReadLine();
            IPrints printer = null;

            if (printerName == "HP")
            {
                printer = new test();
            }
            else if (printerName == "IBM")
            {
                printer = new IBMPrint();
            }
            else if (printerName == "Epsom")
            {
                printer = new EpsomPrint();
            }

            printer.PrintPreview();
            Console.ReadKey();
            printer.Print();
            Console.ReadKey();

            test aa = new test();
            aa.testt();
            Console.ReadKey();
        }
    }
    public class HPPrint : IPrints
    {
        public double a { get; set; }
        public void PrintPreview()
        {
            Console.WriteLine(a.ToString());
        }
        public void Print()
        {
            Console.WriteLine("this is HP Printer");
        }
    }
    public class test : HPPrint
    {
        double zB = 0;
        public double B
        {
            set{zB=value;}
            get { return zB; }
        }
        HPPrint hp = new HPPrint();
        public void testt()
        {
            zB = 10;
            hp.a = 123;
            hp.a += zB;
            hp.PrintPreview();
        }
    }
    public class IBMPrint : IPrints
    {
        public double a { get; set; }
        public void PrintPreview()
        {
            Console.WriteLine("this is IBM Printer");
        }
        public void Print()
        {
            Console.WriteLine("this is IBM Printer");
        }
    }
    public class EpsomPrint : IPrints
    {
        public double a { get; set; }
        public void PrintPreview()
        {
            Console.WriteLine("this is Epsom Printer");
        }
        public void Print()
        {
            Console.WriteLine("this is Epsom Printer");
        }
        public void PrinSt()
        {
            Console.WriteLine("this is Epsom Printer");
        }
    }
}