第一次用文件c#写最最简单的学生信息管理系统

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
namespace 学生信息管理系统
{

class Program
{



    static  void Addstudent()       //新建学生信息
  {
      string ssudent;
    Console.WriteLine("请输入学生的信息(学号、姓名、语文成绩、数学成绩、英语成绩)：");
    FileStream fs = new FileStream("C:\\mystudent.txt", FileMode.Append, FileAccess.Write);
    StreamWriter sw = new StreamWriter(fs, Encoding.Default);
        ssudent = Console.ReadLine();
        sw.WriteLine(ssudent);
        sw.Close();

    }
   static  void Searchstudent() {                        //查询学生信息
       StreamReader sw = new StreamReader("C:\\mystudent.txt");
       string[] array = new string[] { };   //保存学生的各天信息
       string stu;
       string number;
       Console.WriteLine("请输入需要查询的学生的学号：");
       number = Console.ReadLine();
       double allscore, avgscore,alls;
       allscore = avgscore = alls = Convert.ToDouble(0);
       stu = sw.ReadLine();
       while (stu != null)
       {
           array = stu.Split(' ');
           allscore = Convert.ToDouble(array[2]) + Convert.ToDouble(array[3]) + Convert.ToDouble(array[4]);
           alls += allscore;
           if (array[0] == number||array[1]==number)
           {
               avgscore = allscore / 3;
               Console.WriteLine("学生的学号 姓名 语文成绩 数学成绩 英语成绩各是：");
               Console.WriteLine("{0} {1} {2} {3} {4}", array[0], array[1], array[2], array[3], array[4]);
               Console.WriteLine("总成绩是：{0}\n平均成绩是：{1}\n", allscore, avgscore);

           }
           stu = sw.ReadLine();
       }
       Console.WriteLine("\n全部同学的总成绩是：{0}\n", alls);
       sw.Close();


    }
    static void Main(string[] args)
    {
        do
        {
            Console.WriteLine("1、新建学生信息\n2、查询学生信息\n3、退出系统\n");
            int choice;
            Console.WriteLine("请输入你的选择：");
            choice = Convert.ToInt32(Console.ReadLine());
            switch (choice)
            {
                case 1:
               Addstudent();
                    break;
                case 2:
                    Searchstudent();
                    break;

                case 3:
                    Environment.Exit(0);
                    break;


            }

        } while (true);





    }
}

}