C#求解

Question

为什么我做出来只能保存一次，不能永久保存，只能用数组
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;namespace ConsoleApplication2
{
    class Program
    {
        public int[] a = new int[100];
        public string[] b = new string[100];
        int r = 0;
        public void tianjia()
        {
            Console.WriteLine("请输入你添加的用户名");
           
            b[r] =Console.ReadLine();
            Console.WriteLine("请输入你的密码");
            a[r] = Convert.ToInt32(Console.ReadLine());
           r++;
        }
        public void chazhao()
        {
            Console.WriteLine("请输入你要查找的用户名");
            string j = Console.ReadLine();
            Console.WriteLine("请输入密码：");
            int mi = Convert.ToInt32(Console.ReadLine());
            for (int i = 0; i < r; i++)
            {
                if (j == b[i] && mi == a[i])
                {
                    Console.WriteLine("找到用户:用户名{0}密码{1}", b[i], a[i]);
                }
                else
                {
                    Console.WriteLine("你输入的用户名或密码错误");
                }
            }
        }
        public void xiugai()
        {
            Console.WriteLine("请输入你要修改的用户名");
            string xg = Console.ReadLine();
            Console.WriteLine("请输入密码：");
            int xm = Convert.ToInt32(Console.ReadLine());
            for (int i = 0; i <r; i++)
            {
                if (xg == b[i] && xm == a[i])
                {
                    Console.WriteLine("请输入新的用户名：");
                    string xin = Console.ReadLine();
                    Console.WriteLine("请输入新的密码");
                    int xi = Convert.ToInt32(Console.ReadLine());
                    b[i] = xin;
                    a[i] = xi;
                }
            }
        }
        public void xiansi()
        {
            for (int c = 0; c <  r; c++)
            {
                Console.WriteLine("用户名：{0} 密码{1}", b[c], a[c]);
            }
         
        }
        static void Main(string[] args)
        {
            Program sl = new Program();
            Console.WriteLine("1是添加用户；2是查找用户；3是修改用户");
            int mn = Convert.ToInt32(Console.ReadLine());
            switch (mn)
            {
                case 1:
                    sl.tianjia();
                    break;
                case 2:
                    sl.chazhao();
                    break;
                case 3:
                    sl.xiugai();
                    break;
            }
            sl.xiansi();
            
        }
    }
}

Answer 1

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml.Serialization;
using System.IO;
using System.Runtime.Serialization;namespace 将数组转成xml读取
{
    class Program
    {
        static void Main(string[] args)
        {
            Person[] o = Init().ToArray();
            ///
            /// 此处可理解成：
            /// 要转化的对象是什么类型，以转化格式的时候按此类型格式进行转化
            Type type = o.GetType();            //string a = type.FullName;
            string path = Directory.GetCurrentDirectory()+@"\test.xml";
            WriteXmlSerializer(type, o,path);
            ReadeXmlSerializer(type,path);
        }
        /// <summary>
        /// 读取XML，并将其转化成数组
        /// </summary>
        /// <param name="type"></param>
        private static void ReadeXmlSerializer(Type type,string path)
        {
            string temp = "";
            Person[] o = new Person[10];
            //模拟读取数据库数据
            FileStream fs = new FileStream(path, FileMode.Open, FileAccess.Read);
            StreamReader sr = new StreamReader(fs, Encoding.UTF8);
            temp = sr.ReadToEnd();            //将xml转成object[]
            XmlSerializer xml = new XmlSerializer(type);
            using (MemoryStream ms = new MemoryStream(Encoding.UTF8.GetBytes(temp)))
            {
                try
                {
                    o = (Person[])xml.Deserialize(ms);
                }
                catch (Exception)
                {
                    throw;
                }
            }
        }
        /// <summary>
        /// 将数组转化成XML，
        /// </summary>
        /// <param name="type"></param>
        /// <param name="o"></param>
        private static void WriteXmlSerializer(Type type, Person[] o, string path)
        {
            string temp = "";
            DataContractSerializer dcs = new DataContractSerializer(type);
            using (System.IO.MemoryStream ms = new System.IO.MemoryStream())
            {
                using (System.Xml.XmlWriter xw = System.Xml.XmlWriter.Create(ms))
                {
                    dcs.WriteObject(xw,o);
                }
                ms.Position = 0;
                temp = System.Xml.Linq.XElement.Load(ms).ToString();
            }
        }
        /// <summary>
        /// 初使化学生集合
        /// </summary>
        /// <returns></returns>
        private static List<Person> Init()
        {
            List<Person> students = new List<Person>();            Student s0 = new Student { id = 1, name = "张三", sex = false, age = 12, address = "aaaaa" };
            Student s1 = new Student { id = 2, name = "李四", sex = true, age = 22, address = "bbbbbb" };
            Student s2 = new Student { id = 8, name = "王五", sex = false, age = 16, address = "cccc" };
            Student s3 = new Student { id = 14, name = "赵六", sex = true, age = 14, address = "ddddd" };
            Student s4 = new Student { id = 6, name = "二麻子", sex = true, age = 32, address = "eeeee" };
            Student s5 = new Student { id = 3, name = "w", sex = false, age = 26, address = "gggggg" };
            Student s6 = new Student { id = 10, name = "fgg", sex = false, age = 22, address = "jjjjj" };
            Student s7 = new Student { id = 4, name = "qq", sex = true, age = 23, address = "wwwww" };            Teacher t1 = new Teacher() { Id = 1, Name = "aaa", Sex = false };
            Teacher t2 = new Teacher() { Id = 2, Name = "bbb", Sex = true };
            Teacher t3 = new Teacher() { Id = 3, Name = "ccc", Sex = true };
         
            students.Add(s0);
            students.Add(s1);
            students.Add(s2);
            students.Add(s3);
            students.Add(s4);
            students.Add(s5);
            students.Add(s6);
            students.Add(s7);            students.Add(t1);
            students.Add(t2);
            students.Add(t3);
            return students;
        }   

Answer 2

以上是个比较简单的Demo...你只观注以下两个方法就好了
WriteXmlSerializer(type, o,path);
ReadeXmlSerializer(type,path);实体也不要弄那么多个， 多类个继承 时 还要处理其它 东西，所以你只需要 写一个实体测试类就好了