C#控制台应用程序之选课系统

 本程序以文本文件作为存储媒介，实现了一个简化版的选课系统，主要实现了以下功能

1. 对学生信息的增删改查
2. 对课程信息的增删改查
3. 对学生选课的增删改查

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

namespace curricula_Variable
{
    //课程类
    class course
    {
        public course()
        {
            ID = null; namOfCourse = null;
        }
        public course(string id, string nam)
        {
            ID = id; namOfCourse = nam;
        }
        public string namOfCourse;                 //课程名称
        private string ID;                         //课程ID，课程的唯一标示
        public string id
        {
            set { ID = value; }
            get { return ID; }
        }
    }

    //学生类；包含学生基本信息和选课内容
    class student
    {
        public course[] COUR = new course[3];      //所选的课（最多3门）
        public string name;                        //姓名
        private string num;                        //学号，对学生唯一的标示
        public string _num
        {
            get { return num; }
            set { num = value; }
        }
        public string placeNative;                 //籍贯
        public string tel;                         //电话
        public string dormitoryRoom;               //宿舍
    }

    class Program
    {
        //给定一个学生数组（最多100人）
        static student[] stu = new student[100];
        static int countStudent = -1;

        //给定一个课程数组（最多10门课）
        static course[] cour = new course[10];
        static int countCourse = -1;

        static void Main(string[] args)
        {
            //readStuInforFromTxt();
            //readCourInfoFromTxt();
            //readStuCourSelectInforFromTxt();
            homePage();
        HomePage:
            Console.Write("请选择你想使用的功能：");
            int iInput;
        //输入一个数字，如果是0到12，就进行相应操作，否则重新输入
        Input:
            string str = Console.ReadLine();
            if ((Int32.TryParse(str, out iInput)) == false)
            {
                Console.Write("输入的不是整数，请重新输入：");
                goto Input;
            }
            if (iInput >= 0 && iInput < 13)
                switch (iInput)
                {
                    case 1:
                        stuInforAdd();
                        goto HomePage;

                    case 2:
                        stuInforDel();
                        goto HomePage;

                    case 3:
                        stuInforAlter();
                        goto HomePage;

                    case 4:
                        stuInforSelect();
                        goto HomePage;
                    case 5:
                        courseInforAdd();
                        goto HomePage;

                    case 6:
                        courseInforDel();
                        goto HomePage;

                    case 7:
                        courseInforAlter();
                        goto HomePage;

                    case 8:
                        courseInforSelect();
                        goto HomePage;

                    case 9:
                        courseSelectAdd();
                        goto HomePage;

                    case 10:
                        courseSelectDel();
                        goto HomePage;

                    case 11:
                        courseSelectAlter();
                        goto HomePage;

                    case 12:
                        courseSelectSelect();
                        goto HomePage;

                    case 0:
                        Environment.Exit(0);
                        return;
                }
            else
            {
                Console.Write("输入数据超出范围，请重新输入：");
                goto Input;
            }
            Console.ReadKey();
            Environment.Exit(0);
        }

        //主页
        static void homePage()                          
        {
            for (int i = 0; i < 50; i++)
            {
                Console.Write("*");
            }
            Console.WriteLine();
            for (int i = 0; i < 17; i++)
                Console.Write(" ");
            Console.WriteLine("欢迎使用选课系统");
            for (int i = 0; i < 17; i++)
                Console.Write(" ");
            Console.WriteLine("1、 增加学生信息");
            for (int i = 0; i < 17; i++)
                Console.Write(" ");
            Console.WriteLine("2、 删除学生信息");
            for (int i = 0; i < 17; i++)
                Console.Write(" ");
            Console.WriteLine("3、 修改学生信息");
            for (int i = 0; i < 17; i++)
                Console.Write(" ");
            Console.WriteLine("4、 查询学生信息");
            for (int i = 0; i < 17; i++)
                Console.Write(" ");
            Console.WriteLine("5、 增加课程信息");
            for (int i = 0; i < 17; i++)
                Console.Write(" ");
            Console.WriteLine("6、 删除课程信息");
            for (int i = 0; i < 17; i++)
                Console.Write(" ");
            Console.WriteLine("7、 修改课程信息");
            for (int i = 0; i < 17; i++)
                Console.Write(" ");
            Console.WriteLine("8、 查询课程信息");
            for (int i = 0; i < 17; i++)
                Console.Write(" ");
            Console.WriteLine("9、 增加选课内容");
            for (int i = 0; i < 17; i++)
                Console.Write(" ");
            Console.WriteLine("10、删除已选课程");
            for (int i = 0; i < 17; i++)
                Console.Write(" ");
            Console.WriteLine("11、修改课程信息");
            for (int i = 0; i < 17; i++)
                Console.Write(" ");
            Console.WriteLine("12、查询选课信息");
            for (int i = 0; i < 17; i++)
                Console.Write(" ");
            Console.WriteLine("0、 退出选课系统");
            for (int i = 0; i < 50; i++)
            {
                Console.Write("*");
            }
            Console.WriteLine();
        }

        //判断手机号是否合法
        public static bool isPhone(string str_handset)
        {
            return System.Text.RegularExpressions.Regex.IsMatch(str_handset, @"^[1]+[3,5,7,8]+d{9}");
        }

        //判断学号是否合法
        public static bool isNumber(string str_handset)
        {
            return System.Text.RegularExpressions.Regex.IsMatch(str_handset, @"^[1]+[2,3,4,5,6]+[0,1]+d{6}");
        }

        /* 学生信息管理
         * 1、添加学生信息
         * 2、删除学生信息
         * 3、修改学生信息
         * 4、查询学生信息 */

        //学生信息添加，添加学号、姓名
        static void stuInforAdd()
        {
            readStuInforFromTxt();
            Console.Clear();
            student stud = new student();
            Console.Write("请输入学生学号：");
        Input:
            string str = Console.ReadLine();
            if (!isNumber(str) || str.Length != 9)
            {
                Console.Write("学号格式不正确，请重新输入：");
                goto Input;
            }
            else
            {
                int ct = 0, isExit = 0;
                while (stu[ct] != null)
                {
                    if (stu[ct]._num == str)
                    {
                        isExit = -1;
                        break;
                    }
                    else
                        ct++;
                }
                if (isExit == -1)
                {
                    Console.Clear();
                    homePage();
                    Console.WriteLine("该学生信息已存在！");
                    return;
                }
                else
                    stud._num = str;
            }
            Console.Write("请输入学生姓名：");
        Input1:
            string str1 = Console.ReadLine();
            if (str1 == "")
            {
                Console.Write("姓名不能为空，请重新输入：");
                goto Input1;
            }
            else
                stud.name = str1;
            Console.Write("请输入籍贯：");
        Input2:
            string str2 = Console.ReadLine();
            if (str2 == "")
            {
                Console.Write("籍贯不能为空，请重新输入：");
                goto Input2;
            }
            else
                stud.placeNative = str2;

            Console.Write("请输入学生联系电话：");
        Input3:
            str = Console.ReadLine();
            if (!(isPhone(str)) || str.Length != 11)
            {
                Console.Write("联系电话格式不正确，请重新输入：");
                goto Input3;
            }
            else
                stud.tel = str;

            Console.Write("请输入学生宿舍号：");
        Input4:
            int m;
            str = Console.ReadLine();
            if (!(Int32.TryParse(str, out m)))
            {
                Console.Write("宿舍号格式不正确，请重新输入：");
                goto Input4;
            }
            else
                stud.dormitoryRoom = str;
            stu[++countStudent] = stud;
            Console.Clear();
            homePage();
            saveStuInforToTxt();
            Console.WriteLine("添加成功！");
        }

        //学生信息删除，删除个人所有信息
        static void stuInforDel()
        {
            readStuInforFromTxt();
            Console.Clear();
            Console.Write("请输入您想删除的学生学号：");
            string i = Console.ReadLine();
            Input:
            string str = Console.ReadLine();
            if (!isNumber(i) || i.Length != 9)
            {
                Console.Write("学号格式不正确，请重新输入：");
                goto Input;
            }
            int n = 0;
            homePage();
            while (stu[n] != null)
            {
                if (stu[n]._num == i)
                {
                    List<student> list = stu.ToList();
                    list.RemoveAt(n);
                    student[] newarr = list.ToArray();
                    stu = newarr;
                    countStudent--;
                    Console.WriteLine("删除成功！");
                    saveStuInforToTxt();
                    return;
                }
                else
                    n++;
            }
            Console.WriteLine("查无此人！");
        }

        //学生信息修改，修改除学号以外的信息
        static void stuInforAlter()
        {
            readStuInforFromTxt();
            Console.Clear();
            Console.Write("请输入您想修改的学生的学号：");
        Input:
            string i = Console.ReadLine();
            if (!isNumber(i) || i.Length != 9)
            {
                Console.Write("学号格式不正确，请重新输入：");
                goto Input;
            }
            string str = "";
            int n = 0;
            homePage();
            while (stu[n] != null)
            {
                if (stu[n]._num == i)
                {
                    Console.Write("请输入修改后的姓名：");
                Input1:
                    str = Console.ReadLine();
                    if (str == "")
                    {
                        Console.Write("姓名不能为空，请重新输入：");
                        goto Input1;
                    }
                    else
                        stu[n].name = str;

                    Console.Write("请输入修改后的籍贯：");
                Input2:
                    str = Console.ReadLine();
                    if (str == "")
                    {
                        Console.Write("籍贯不能为空，请重新输入：");
                        goto Input2;
                    }
                    else
                        stu[n].placeNative = str;

                    Console.Write("请输入修改后的联系电话：");
                Input3:
                    str = Console.ReadLine();
                    if (!isPhone(str) || str.Length != 11)
                    {
                        Console.Write("联系电话格式不正确，请重新输入：");
                        goto Input3;
                    }
                    else
                        stu[n].tel = str;

                    Console.Write("请输入修改后的宿舍号：");
                Input4:
                    int m;
                    str = Console.ReadLine();
                    if (!(Int32.TryParse(str, out m)))
                    {
                        Console.Write("宿舍号格式不正确，请重新输入：");
                        goto Input4;
                    }
                    else
                        stu[n].dormitoryRoom = str;
                    Console.Clear();
                    homePage();
                    saveStuInforToTxt();
                    Console.WriteLine("修改成功！");
                    return;
                }
                else
                    n++;
            }
            Console.WriteLine("查无此人！");
        }

        //学生信息查询，通过学号查询姓名
        static void stuInforSelect()
        {
            readStuInforFromTxt();
            Console.Clear();
            Console.Write("请输入您想查询的学生学号：");
        Input:
            string i = Console.ReadLine();
            if (!isNumber(i))
            {
                Console.Write("学号格式不正确，请重新输入：");
                goto Input;
            }
            int n = 0;
            homePage();
            while (stu[n] != null)
            {
                if (stu[n]._num == i)
                {
                    Console.WriteLine("您所查询的学生的姓名为：{0}", stu[n].name);
                    Console.WriteLine("您所查询的学生的籍贯为：{0}", stu[n].placeNative);
                    Console.WriteLine("您所查询的学生的电话为：{0}", stu[n].tel);
                    Console.WriteLine("您所查询的学生的宿舍号：{0}", stu[n].dormitoryRoom);
                    saveStuInforToTxt();
                    return;
                }
                else
                    n++;
            }
            Console.WriteLine("查无此人！");
        }


        /* 课程信息管理
         * 1、增加课程信息
         * 2、删除课程信息
         * 3、修改课程信息
         * 4、查询课程信息 */

        //课程信息添加，通过添加课程ID添加课程
        static void courseInforAdd()
        {
            readCourInfoFromTxt();
            if (countCourse == 9)
            {
                Console.Clear();
                homePage();
                saveCourseInforToTxt();
                Console.WriteLine("课程已满！若要继续添加，请先删除部分课程！");
                return;
            }
            Console.Clear();
            course Cour = new course();
            Console.Write("请输入课程ID：");
        Input:
            string str = Console.ReadLine();
            int m;
            if (!(Int32.TryParse(str, out m)))
            {
                Console.Write("课程ID格式不正确，请重新输入：");
                goto Input;
            }
            else
            {
                int ct = 0, isExit = 0;
                while (cour[ct] != null)
                {
                    if (cour[ct].id == str)
                    {
                        isExit = -1;
                        break;
                    }
                    else
                        ct++;
                }
                if (isExit == -1)
                {
                    Console.Clear();
                    homePage();
                    saveCourseInforToTxt();
                    Console.WriteLine("该课程信息已存在！");
                    return;
                }
                else
                    Cour.id = str;
            }
            Console.Write("请输入课程名称：");
        Input1:
            string str1 = Console.ReadLine();
            if (str1 == "")
            {
                Console.Write("课程名称不能为空，请重新输入：");
                goto Input1;
            }
            else
                Cour.namOfCourse = str1;
            cour[++countCourse] = Cour;
            Console.Clear();
            homePage();
            Console.WriteLine("添加成功！");
            saveCourseInforToTxt();
        }

        //课程信息删除，通过课程ID删除相关课程
        static void courseInforDel()
        {
            readCourInfoFromTxt();
            Console.Clear();
            Console.Write("请输入您想删除的课程ID：");
            string i = Console.ReadLine();
            int n = 0;
            homePage();
            Console.Clear();
            while (n<10&&cour[n] != null)
            {
                if (cour[n].id == i)
                {
                    List<course> list = cour.ToList();
                    list.RemoveAt(n);
                    course[] newarr = list.ToArray();
                    cour = newarr;
                    countCourse--;
                    homePage();
                    Console.WriteLine("删除成功！");
                    for (int k = 0; k < countStudent; k++)
                    {
                        for (int j = 0; stu[k].COUR[j] != null; j++)
                        {
                            if (stu[k].COUR[j].id == i)
                            {
                                List<course> list1 = stu[k].COUR.ToList();
                                list1.RemoveAt(j);
                                course[] newarr1 = list1.ToArray();
                                stu[k].COUR = newarr1;
                            }
                        }
                    }
                    saveCourseInforToTxt();
                    return;
                }
                else
                    n++;
            }
            homePage();
            saveCourseInforToTxt();
            Console.WriteLine("查无此课程！");
        }

        //课程信息修改，通过ID删除除ID以外的信息
        static void courseInforAlter()
        {
            readCourInfoFromTxt();
            Console.Clear();
            Console.Write("请输入您想修改的课程的ID：");
        Input1:
            string i = Console.ReadLine();
            int n = 0;
            while (cour[n] != null)
            {
                if (cour[n].id == i)
                {
                    Console.Write("请输入修改后的课程名称：");
                    string str1 = Console.ReadLine();
                    if (str1 == "")
                    {
                        Console.Write("课程名称不能为空，请重新输入：");
                        goto Input1;
                    }
                    else
                        cour[n].namOfCourse = str1;
                    homePage();
                    saveCourseInforToTxt();
                    Console.WriteLine("修改成功！");
                    return;
                }
                else
                    n++;
            }
            homePage();
            saveCourseInforToTxt();
            Console.WriteLine("查无此课程！");
        }

        //课程查询，通过ID查询课程
        static void courseInforSelect()
        {
            readCourInfoFromTxt();
            Console.Clear();
            Console.Write("请输入您想查询的课程ID：");
            string i = Console.ReadLine();
            int n = 0;
            homePage();
            while (cour[n] != null)
            {
                if (cour[n].id == i)
                {
                    saveCourseInforToTxt();
                    Console.WriteLine("您所查询的课程名称为：{0}", cour[n].namOfCourse);
                    return;
                }
                else
                    n++;
            }
            saveCourseInforToTxt();
            Console.WriteLine("查无此课程！");
        }


        /* 选课管理
         * 1、增加所选课程
         * 2、取消已选课程
         * 3、修改已选课程
         * 4、查询已选课程 */

        //通过学号和课程ID增加个人选的课程
        static void courseSelectAdd()
        {
            readCourInfoFromTxt();
            readStuInforFromTxt();
            readStuCourSelectInforFromTxt();
            if (stu[0] == null)
            {
                Console.Clear();
                homePage();
                Console.WriteLine("暂无学生信息！");
                saveCourseInforToTxt();
                saveStuCourSelectInforToTxt();
                saveStuInforToTxt();
                return;
            }
            if (cour[0] == null)
            {
                Console.Clear();
                homePage();
                Console.WriteLine("暂无课程信息！");
                saveCourseInforToTxt();
                saveStuCourSelectInforToTxt();
                saveStuInforToTxt();
                return;
            }
            Console.Clear();
            Console.Write("请输入您的学号：");
        Input:
            string str = Console.ReadLine();
            if (!isNumber(str) || str.Length != 9)
            {
                Console.Write("学号格式不正确，请重新输入：");
                goto Input;
            }
            else
            {
                int i = 0;
                while(stu[i]._num != str)
                {
                    i++;
                    if (i >countStudent)
                    {
                        Console.Clear();
                        homePage();
                        Console.WriteLine("查无此人！");
                        saveCourseInforToTxt();
                        saveStuCourSelectInforToTxt();
                        saveStuInforToTxt();
                        return;
                    }
                }
                Console.Write("请输入您想选的课程名称：");
                str = Console.ReadLine();
                int l = 0;
                for (; l<10&&cour[l] != null; l++) { }
                int j = 0;
            here:
                if (cour[j] != null && cour[j].namOfCourse != str)
                {
                    if (j < l )
                    {
                        j++;
                        goto here;
                    }
                    else
                    {
                        Console.Clear();
                        homePage();
                        Console.WriteLine("查无此课程！");
                        saveCourseInforToTxt();
                        saveStuCourSelectInforToTxt();
                        saveStuInforToTxt();
                        return;
                    }
                }
                else
                {
                    if (cour[j] == null)
                    {
                        Console.Clear();
                        homePage();
                        Console.WriteLine("查无此课程！");
                        saveCourseInforToTxt();
                        saveStuCourSelectInforToTxt();
                        saveStuInforToTxt();
                        return;
                    }
                    if ((stu[i].COUR[0]!=null&&stu[i].COUR[0].id == cour[j].id) || (stu[i].COUR[1]!=null&&stu[i].COUR[1].id== cour[j].id) || (stu[i].COUR[2]!=null&&stu[i].COUR[2].id == cour[j].id))
                    {
                        Console.Clear();
                        homePage();
                        Console.WriteLine("该门课已选，不能重复提交！");
                        saveCourseInforToTxt();
                        saveStuCourSelectInforToTxt();
                        saveStuInforToTxt();
                        return;
                    }
                    if (stu[i].COUR[0] == null)
                        stu[i].COUR[0] = cour[j];
                    else if
                        (stu[i].COUR[1] == null)
                        stu[i].COUR[1] = cour[j];
                    else if
                        (stu[i].COUR[2] == null)
                        stu[i].COUR[2] = cour[j];
                    else
                    {
                        homePage();
                        Console.WriteLine("您所选课程已达最大数额！");
                        saveCourseInforToTxt();
                        saveStuCourSelectInforToTxt();
                        saveStuInforToTxt();
                        return;
                    }
                    Console.Clear();
                    homePage();
                    Console.WriteLine("选课成功！");
                    saveCourseInforToTxt();
                    saveStuCourSelectInforToTxt();
                    saveStuInforToTxt();
                }
            }
        }

        //删除选课，通过学号和课程ID删除个人选的课程
        static void courseSelectDel()
        {
            readStuInforFromTxt();
            readCourInfoFromTxt();
            readStuCourSelectInforFromTxt();
            if (stu[0] == null)
            {
                Console.Clear();
                homePage();
                Console.WriteLine("暂无学生信息！");
                saveCourseInforToTxt();
                saveStuCourSelectInforToTxt();
                saveStuInforToTxt();
                return;
            }
            if (cour[0] == null)
            {
                Console.Clear();
                homePage();
                Console.WriteLine("暂无课程信息！");
                saveCourseInforToTxt();
                saveStuCourSelectInforToTxt();
                saveStuInforToTxt();
                return;
            }
            Console.Clear();
            Console.Write("请输入您的学号：");
        Input:
            string str = Console.ReadLine();
            if (!isNumber(str) || str.Length != 9)
            {
                Console.Write("学号格式不正确，请重新输入：");
                goto Input;
            }
            else
            {
                int l = 0;
                for (; stu[l] != null; l++) { }
                int i = 0;
            Judge:
                if (stu[i]._num != str)
                {
                    if (i < l - 1)
                    {
                        i++;
                        goto Judge;
                    }
                    else
                    {
                        homePage();
                        Console.WriteLine("查无此人！");
                    }
                    saveCourseInforToTxt();
                    saveStuCourSelectInforToTxt();
                    saveStuInforToTxt();
                    return;
                }
                else
                    Console.Write("请输入您想取消的课程名称：");
                str = Console.ReadLine();
                l = 0;
                for (; l<10&&cour[l] != null; l++) { }
                int j = 0;
                Here:
                if (cour[j]!=null&&cour[j].namOfCourse != str)
                {
                    if (j < l)
                    {
                        j++;
                        goto Here;
                    }
                    else
                    {
                        Console.Clear();
                        homePage();
                        Console.Write("查无此课程！");
                        saveCourseInforToTxt();
                        saveStuCourSelectInforToTxt();
                        saveStuInforToTxt();
                        return;
                    }
                }
                else
                {
                    if (stu[i].COUR[0] == null)
                    {
                        Console.Clear();
                        homePage();
                        Console.WriteLine("您尚未选该门课！");
                        saveCourseInforToTxt();
                        saveStuCourSelectInforToTxt();
                        saveStuInforToTxt();
                        return;
                    }
                    else if (stu[i].COUR[1] == null)
                    {
                        if (stu[i].COUR[0].namOfCourse == str)
                        {
                            stu[i].COUR[0] = null;
                            Console.Clear();
                            homePage();
                            Console.WriteLine("取消成功！");
                            saveCourseInforToTxt();
                            saveStuCourSelectInforToTxt();
                            saveStuInforToTxt();
                            return;
                        }
                        else
                        {
                            Console.Clear();
                            homePage();
                            Console.WriteLine("您尚未选该门课！");
                            saveCourseInforToTxt();
                            saveStuCourSelectInforToTxt();
                            saveStuInforToTxt();
                            return;
                        }
                    }
                    else if (stu[i].COUR[2] == null)
                    {
                        if (stu[i].COUR[0].namOfCourse == str)
                        {
                            stu[i].COUR[0] = stu[i].COUR[1];
                            stu[i].COUR[1] = null;
                            Console.Clear();
                            homePage();
                            Console.WriteLine("取消成功！");
                            saveCourseInforToTxt();
                            saveStuCourSelectInforToTxt();
                            saveStuInforToTxt();
                            return;
                        }
                        else if (stu[i].COUR[1].namOfCourse == str)
                        {
                            stu[i].COUR[1] = null;
                            Console.Clear();
                            homePage();
                            saveCourseInforToTxt();
                            saveStuCourSelectInforToTxt();
                            saveStuInforToTxt();
                            Console.WriteLine("取消成功！");
                            return;
                        }
                        else
                        {
                            Console.Clear();
                            homePage();
                            Console.WriteLine("您尚未选该门课！");
                            saveCourseInforToTxt();
                            saveStuCourSelectInforToTxt();
                            saveStuInforToTxt();
                            return;
                        }
                    }
                    else
                    {
                        if (stu[i].COUR[0].namOfCourse == str)
                        {
                            stu[i].COUR[0] = stu[i].COUR[1];
                            stu[i].COUR[1] = stu[i].COUR[2];
                            stu[i].COUR[2] = null;
                            Console.Clear();
                            homePage();
                            Console.WriteLine("取消成功！");
                            saveCourseInforToTxt();
                            saveStuCourSelectInforToTxt();
                            saveStuInforToTxt();
                            return;
                        }
                        else if (stu[i].COUR[1].namOfCourse == str)
                        {
                            stu[i].COUR[1] = stu[i].COUR[2];
                            stu[i].COUR[2] = null;
                            Console.Clear();
                            homePage();
                            Console.WriteLine("取消成功！");
                            saveCourseInforToTxt();
                            saveStuCourSelectInforToTxt();
                            saveStuInforToTxt();
                            return;
                        }
                        else if (stu[i].COUR[2].namOfCourse == str)
                        {
                            stu[i].COUR[2] = null;
                            Console.Clear();
                            homePage();
                            Console.WriteLine("取消成功！");
                            saveCourseInforToTxt();
                            saveStuCourSelectInforToTxt();
                            saveStuInforToTxt();
                            return;
                        }
                        else
                        {
                            Console.Clear();
                            homePage();
                            Console.WriteLine("您尚未选该门课！");
                            saveCourseInforToTxt();
                            saveStuCourSelectInforToTxt();
                            saveStuInforToTxt();
                            return;
                        }
                    }
                }
            }
        }

        //修改选课，通过学号和课程ID修改所选的课程
        static void courseSelectAlter()
        {
            readStuInforFromTxt();
            readCourInfoFromTxt();
            readStuCourSelectInforFromTxt();
            if (stu[0] == null)
            {
                Console.Clear();
                homePage();
                Console.WriteLine("暂无学生信息！");
                saveCourseInforToTxt();
                saveStuCourSelectInforToTxt();
                saveStuInforToTxt();
                return;
            }
            if (cour[0] == null)
            {
                Console.Clear();
                homePage();
                Console.WriteLine("暂无课程信息！");
                saveCourseInforToTxt();
                saveStuCourSelectInforToTxt();
                saveStuInforToTxt();
                return;
            }
            Console.Clear();
            Console.Write("请输入您的学号：");
            string str1 = "";
        Input:
            string str = Console.ReadLine();
            if (!isNumber(str) || str.Length != 9)
            {
                Console.Write("学号格式不正确，请重新输入：");
                goto Input;
            }
            else
            {
                int l = 0;
                for (; stu[l] != null; l++) { }
                int i = 0;
                hERe:
                if (stu[i]._num != str)
                {
                    if (i < l - 1)
                    {
                        i++;
                        goto hERe;
                    }
                    else
                    {
                        homePage();
                        Console.WriteLine("查无此人！");
                        saveCourseInforToTxt();
                        saveStuCourSelectInforToTxt();
                        saveStuInforToTxt();
                        return;
                    }
                }
                else
                    Console.Write("请输入您想修改之后的课程名称：");
                str = Console.ReadLine();
                l = 0;
                for (; cour[l] != null; l++) { }
                int j = 0;
                hEre:
                if (cour[j].namOfCourse != str)
                {
                    if (j < l - 1)
                    {
                        j++;
                        goto hEre;
                    }
                    else
                        Console.Write("查无此课程！");
                    saveCourseInforToTxt();
                    saveStuCourSelectInforToTxt();
                    saveStuInforToTxt();
                    return;
                }
                else
                {
                    //输入不想要的课，判断已选课中是否存在，若存在进行替换，反之函数结束
                    Console.Write("请输入您不想要的课程名称：");
                    str1 = Console.ReadLine();

                    if (stu[i].COUR[0] == null)
                    {
                        Console.Clear();
                        homePage();
                        Console.Write("您尚未选门课，不能进行修改操作！");
                        saveCourseInforToTxt();
                        saveStuCourSelectInforToTxt();
                        saveStuInforToTxt();
                        return;
                    }
                    else if (stu[i].COUR[1] == null)
                    {
                        if (stu[i].COUR[0].namOfCourse == str1)
                        {
                            stu[i].COUR[0] = cour[j];
                            Console.Clear();
                            homePage();
                            Console.WriteLine("修改成功！");
                            saveCourseInforToTxt();
                            saveStuCourSelectInforToTxt();
                            saveStuInforToTxt();
                            return;
                        }
                        else
                        {
                            Console.Clear();
                            homePage();
                            Console.WriteLine("您尚未选该门课！");
                            saveCourseInforToTxt();
                            saveStuCourSelectInforToTxt();
                            saveStuInforToTxt();
                            return;
                        }
                    }
                    else if (stu[i].COUR[2] == null)
                    {
                        if (stu[i].COUR[0].namOfCourse == str1)
                        {
                            stu[i].COUR[0] = cour[j];
                            Console.Clear();
                            homePage();
                            Console.WriteLine("修改成功！");
                            saveCourseInforToTxt();
                            saveStuCourSelectInforToTxt();
                            saveStuInforToTxt();
                            return;
                        }
                        else if (stu[i].COUR[1].namOfCourse == str1)
                        {
                            stu[i].COUR[1] = cour[j];
                            Console.Clear();
                            homePage();
                            Console.WriteLine("修改成功！");
                            saveCourseInforToTxt();
                            saveStuCourSelectInforToTxt();
                            saveStuInforToTxt();
                            return;
                        }
                        else
                        {
                            Console.Clear();
                            homePage();
                            Console.WriteLine("您尚未选该门课！");
                            saveCourseInforToTxt();
                            saveStuCourSelectInforToTxt();
                            saveStuInforToTxt();
                            return;
                        }
                    }
                    else
                    {
                        if (stu[i].COUR[0].namOfCourse == str1)
                        {
                            stu[i].COUR[0] = cour[j];
                            Console.Clear();
                            homePage();
                            Console.WriteLine("修改成功！");
                            saveCourseInforToTxt();
                            saveStuCourSelectInforToTxt();
                            saveStuInforToTxt();
                            return;
                        }
                        else if (stu[i].COUR[1].namOfCourse == str1)
                        {
                            stu[i].COUR[1] = cour[j];
                            Console.Clear();
                            homePage();
                            Console.WriteLine("修改成功！");
                            saveCourseInforToTxt();
                            saveStuCourSelectInforToTxt();
                            saveStuInforToTxt();
                            return;
                        }
                        else if (stu[i].COUR[2].namOfCourse == str1)
                        {
                            stu[i].COUR[2] = cour[j];
                            Console.Clear();
                            homePage();
                            Console.WriteLine("修改成功！");
                            saveCourseInforToTxt();
                            saveStuCourSelectInforToTxt();
                            saveStuInforToTxt();
                            return;
                        }
                        else
                        {
                            Console.Clear();
                            homePage();
                            Console.WriteLine("您尚未选该门课！");
                            saveCourseInforToTxt();
                            saveStuCourSelectInforToTxt();
                            saveStuInforToTxt();
                            return;
                        }
                    }
                }
            }
        }

        //查找选课，通过学号查找所选的课程
        static void courseSelectSelect()
        {
            readStuInforFromTxt();
            readCourInfoFromTxt();
            readStuCourSelectInforFromTxt();
            int i = 0;
            if (stu[0] == null)
            {
                Console.Clear();
                homePage();
                Console.WriteLine("暂无学生信息！");
                saveCourseInforToTxt();
                saveStuCourSelectInforToTxt();
                saveStuInforToTxt();
                return;
            }
            if (cour[0] == null)
            {
                Console.Clear();
                homePage();
                Console.WriteLine("暂无课程信息！");
                saveCourseInforToTxt();
                saveStuCourSelectInforToTxt();
                saveStuInforToTxt();
                return;
            }
            Console.Clear();
            Console.Write("请输入您的学号：");
        Input:
            string str = Console.ReadLine();
            if (!isNumber(str) || str.Length != 9)
            {
                Console.Write("学号格式不正确，请重新输入：");
                goto Input;
            }
            else
            {
                int l = 0;
                for (; stu[l] != null; l++) { }
            HERE:
                if (stu[i]!=null&&stu[i]._num != str)
                {
                    if (i < l - 1)
                    {
                        i++;
                        goto HERE;
                    }
                    else
                    {
                        saveCourseInforToTxt();
                        saveStuCourSelectInforToTxt();
                        saveStuInforToTxt();
                        homePage();
                        Console.WriteLine("查无此人！");
                        return;
                    }
                }
                else
                {
                    homePage();
                    if (stu[i].COUR[2] != null)
                        Console.WriteLine("您所查找的学生的选课内容为：{0}、{1}、{2}", stu[i].COUR[0].namOfCourse, stu[i].COUR[1].namOfCourse, stu[i].COUR[2].namOfCourse);
                    else if (stu[i].COUR[1] != null)
                        Console.WriteLine("您所查找的学生的选课内容为：{0}、{1}", stu[i].COUR[0].namOfCourse, stu[i].COUR[1].namOfCourse);
                    else if (stu[i].COUR[0] != null)
                        Console.WriteLine("您所查找的学生的选课内容为：{0}", stu[i].COUR[0].namOfCourse);
                    else
                        Console.WriteLine("该生尚未选课！");
                }
            }
            saveCourseInforToTxt();
            saveStuCourSelectInforToTxt();
            saveStuInforToTxt();
        }


        /* 文件流操作
         * 1、读取学生信息
         * 2、写入学生信息
         * 3、读取课程信息
         * 4、写入课程信息
         * 5、读取选课信息
         * 6、写入选课信息*/

        //从txt文件中读取原始学生数据
        static void readStuInforFromTxt()
        {
            FileStream mFile = new FileStream("stuInfor.txt", FileMode.OpenOrCreate);
            mFile.Close();
            mFile.Dispose();
            int countLinesInTxt = File.ReadAllLines("stuInfor.txt").Length;
            FileStream aFile = new FileStream("stuInfor.txt", FileMode.OpenOrCreate);

            StreamReader sr = new StreamReader(aFile, Encoding.Default);   //没有Encoding.Default，读取到的汉字会乱码
            string[] data;
            string strReadFromTxt = "";
            for (int i = 0; i < countLinesInTxt; i++)
            {
                strReadFromTxt = sr.ReadLine();
                data = strReadFromTxt.Split(' ');
                if (data[0] == "")
                    continue;
                student studFromTxt = new student();
                studFromTxt._num = data[0];
                studFromTxt.name = data[1];
                studFromTxt.placeNative = data[2];
                studFromTxt.tel = data[3];
                studFromTxt.dormitoryRoom = data[4];
                for (int j = 0; j < data.Length - 5; j += 2)
                {
                    course Cour = new course();
                    Cour.id = data[j / 2];
                    Cour.namOfCourse = data[j / 2 + 1];
                    studFromTxt.COUR[j / 2] = Cour;
                    Cour = null;
                }
                stu[++countStudent] = studFromTxt;
                studFromTxt = null;
            }
            sr.Close();
            sr.Dispose();
            aFile.Close();
            aFile.Dispose();
        }

        //将学生数据保存到txt文件中
        static void saveStuInforToTxt()
        {
            FileStream saveFile = new FileStream("stuInfor.txt", FileMode.Truncate);
            StreamWriter sw = new StreamWriter(saveFile, Encoding.Default);

            int m = -1;
            do
            {
                m++;
            }
            while (stu[m] != null);
            for (int i = 0; i < m; i++)
            {
                string str = stu[i]._num + " " + stu[i].name + " " + stu[i].placeNative + " " + stu[i].tel + " " + stu[i].dormitoryRoom;
                sw.WriteLine(str);
                countStudent--;
            }
            sw.Close();
            saveFile.Close();
        }

        //从txt文件中读取原始课程数据
        static void readCourInfoFromTxt()
        {
            FileStream mFile = new FileStream("courseInfor.txt", FileMode.OpenOrCreate);
            mFile.Close();
            int countLinesInTxt = File.ReadAllLines("courseInfor.txt").Length;
            FileStream aFile = new FileStream("courseInfor.txt", FileMode.OpenOrCreate);

            StreamReader sr = new StreamReader(aFile, Encoding.Default);   //没有Encoding.Default，读取到的汉字会乱码
            string[] data;
            string strReadFromTxt = "";
            for (int i = 0; i < countLinesInTxt; i++)
            {
                strReadFromTxt = sr.ReadLine();
                data = strReadFromTxt.Split(' ');
                if (data[0] == "")
                    continue;
                course courseFromTxt = new course();
                courseFromTxt.id = data[0];
                courseFromTxt.namOfCourse = data[1];
                cour[++countCourse] = courseFromTxt;
                courseFromTxt = null;
            }
            sr.Close();
            aFile.Close();
        }

        //将课程数据保存到txt文件中
        static void saveCourseInforToTxt()
        {
            FileStream saveFile = new FileStream("courseInfor.txt", FileMode.Truncate);
            StreamWriter sw = new StreamWriter(saveFile, Encoding.Default);

            int m = -1;
            do
            {
                m++;
                if (m == 10)
                    break;
            }
            while (cour[m] != null);
            for (int i = 0; i < m; i++)
            {
                string str = cour[i].id + " " + cour[i].namOfCourse;
                sw.WriteLine(str);
                countCourse--;
            }
            sw.Close();
            saveFile.Close();
        }

        //从txt文件中读取原始选课数据
        static void readStuCourSelectInforFromTxt()
        {
            FileStream mFile = new FileStream("CourSelect.txt", FileMode.OpenOrCreate);
            mFile.Close();
            mFile.Dispose();
            int countLinesInTxt = File.ReadAllLines("CourSelect.txt").Length;
            FileStream aFile = new FileStream("CourSelect.txt", FileMode.Open);

            StreamReader sr = new StreamReader(aFile, Encoding.Default);   //没有Encoding.Default，读取到的汉字会乱码
            string strReadFromTxt = "";
            for (int i = 0; i < countLinesInTxt; i++)
            {
                strReadFromTxt = sr.ReadLine();
                string[] strData = strReadFromTxt.Split(' ');
                if (strData[0] == "")
                    continue;
                student STU = new student();
                STU._num = strData[0];
                STU.name = strData[1];
                STU.placeNative = strData[2];
                STU.tel = strData[3];
                STU.dormitoryRoom = strData[4];
                for (int k = 0; k < strData.Length - 5; k += 2)
                {
                    course Cou = new course();
                    Cou.id = strData[5+k];
                    Cou.namOfCourse = strData[6+k];
                    STU.COUR[k / 2] = Cou;
                    Cou = null;
                }

                //在已导入的数据中查找该学生信息，并补充其选课信息
                for (int j = 0; j <= countStudent; j++)                 
                {
                    if (stu[j]._num == STU._num)
                        stu[j] = STU;
                }
                STU = null;
            }
            aFile.Close();
            aFile.Dispose();
        }

        //将学生数据保存到txt文件中
        static void saveStuCourSelectInforToTxt()
        {
            FileStream saveStuCourFile = new FileStream("CourSelect.txt", FileMode.Truncate);
            StreamWriter sw = new StreamWriter(saveStuCourFile, Encoding.Default);
            int m = -1;
            do
            {
                m++;
            }
            while (stu[m] != null);
            for (int i = 0; i < m; i++)
            {
                string str = "";
                if (stu[i].COUR[0] != null)
                {
                    str = stu[i]._num + " " + stu[i].name + " " + stu[i].placeNative + " " + stu[i].tel + " "
                            + stu[i].dormitoryRoom;
                    for (int j = 0; j < 3&&stu[i].COUR[j] != null; j++)
                        str += " " + stu[i].COUR[j].id + " " + stu[i].COUR[j].namOfCourse;
                    sw.WriteLine(str);
                }
            }
            sw.Close();
            saveStuCourFile.Close();
        }
    }
}

作者：耑新新，发布于  博客园

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