diff --git a/Homework/Program.cs b/Homework/Program.cs index b728a41..813174a 100644 --- a/Homework/Program.cs +++ b/Homework/Program.cs @@ -1,7 +1,9 @@ // See https://aka.ms/new-console-template for more information using System; using System.Collections.Generic; +using System.ComponentModel.DataAnnotations; using System.IO; +using static System.Formats.Asn1.AsnWriter; namespace StudentManagementSystem { @@ -9,43 +11,59 @@ namespace StudentManagementSystem public enum Grade { // TODO: 定义成绩等级 F(0), D(60), C(70), B(80), A(90) - + F = 0, + D = 60, + C = 70, + B = 80, + A = 90 } // 泛型仓储接口 public interface IRepository { // TODO: 定义接口方法 - // Add(T item) - // Remove(T item) 返回bool - // GetAll() 返回List - // Find(Func predicate) 返回List - + void Add(T item); + bool Remove(T item); + List GetAll(); + List Find(Func predicate); + } // 学生类 public class Student : IComparable { // TODO: 定义字段 StudentId, Name, Age - - + public string StudentId { get; } + public string Name { get; } + public int Age { get; } + public Student(string studentId, string name, int age) { // TODO: 实现构造方法，包含参数验证（空值检查） - + if (string.IsNullOrWhiteSpace(studentId)) + throw new ArgumentException("学号不能为空"); + if (string.IsNullOrWhiteSpace(name)) + throw new ArgumentException("姓名不能为空"); + if (age <= 0 || age > 120) + throw new ArgumentException("年龄必须在合理范围内"); + + StudentId = studentId; + Name = name; + Age = age; } public override string ToString() { // TODO: 返回格式化的学生信息字符串 - + return $"学号:{StudentId}\t姓名:{Name}\t年龄:{Age}"; } // TODO: 实现IComparable接口，按学号排序 // 提示：使用string.Compare方法 public int CompareTo(Student? other) { - + if (other == null) return 1; + return string.Compare(StudentId, other.StudentId, StringComparison.Ordinal); } public override bool Equals(object? obj) @@ -63,18 +81,25 @@ public override int GetHashCode() public class Score { // TODO: 定义字段 Subject, Points - - + public string Subject { get; } + public double Points { get; } + public Score(string subject, double points) { // TODO: 实现构造方法，包含参数验证 - + if (string.IsNullOrWhiteSpace(subject)) + throw new ArgumentException("科目名称不能为空"); + if (points < 0 || points > 100) + throw new ArgumentException("分数必须在0-100之间"); + + Subject = subject; + Points = points; } public override string ToString() { // TODO: 返回格式化的成绩信息 - + return $"科目:{Subject}\t成绩:{Points}"; } } @@ -83,39 +108,53 @@ public class StudentManager : IRepository { // TODO: 定义私有字段存储学生列表 // 提示：使用List存储 - + private List _students = new List(); + public void Add(Student item) { // TODO: 实现添加学生的逻辑 // 1. 参数验证 // 2. 添加到列表 - + if (item == null) throw new ArgumentNullException(nameof(item), "学生不能为空！"); + if (_students.Contains(item)) throw new InvalidOperationException($"学号 {item.StudentId} 已存在！"); + _students.Add(item); } public bool Remove(Student item) { // TODO: 实现Remove方法 - + if (item == null) return false; + return _students.Remove(item); } public List GetAll() { // TODO: 返回学生列表的副本 - + return new List(_students); } public List Find(Func predicate) { // TODO: 使用foreach循环查找符合条件的学生 - + if (predicate == null) throw new ArgumentNullException(nameof(predicate), "查询·条件不能为空！"); + var result = new List(); + foreach (var student in _students) + { + if (predicate(student)) + { + result.Add(student); + } + } + return result; } // 查找年龄在指定范围内的学生 public List GetStudentsByAge(int minAge, int maxAge) { // TODO: 使用foreach循环和if判断实现年龄范围查询 - + if (minAge < 0 || maxAge > 120) throw new ArgumentException("年龄范围不合法！"); + return Find(student => (student.Age >= minAge && student.Age <= maxAge)); } } @@ -124,46 +163,89 @@ public class ScoreManager { // TODO: 定义私有字段存储成绩字典 // 提示：使用Dictionary>存储 - + private readonly Dictionary> _scores = new Dictionary>(); public void AddScore(string studentId, Score score) { // TODO: 实现添加成绩的逻辑 // 1. 参数验证 + if (string.IsNullOrWhiteSpace(studentId)) throw new ArgumentException(nameof(studentId), "学号不能为空！"); + if (score == null) throw new ArgumentNullException(nameof(score), "成绩不能为空！"); // 2. 初始化学生成绩列表（如不存在） + if (!_scores.ContainsKey(studentId)) + { + _scores[studentId] = new List(); + } // 3. 添加成绩 - + _scores[studentId].Add(score); } public List GetStudentScores(string studentId) { // TODO: 获取指定学生的所有成绩 - + if (_scores.TryGetValue(studentId, out var studentScores)) + { + return new List(studentScores); + } + return new List(); } public double CalculateAverage(string studentId) { // TODO: 计算指定学生的平均分 // 提示：使用foreach循环计算总分，然后除以科目数 - + var studentScores = GetStudentScores(studentId); + double sum = 0; + if (studentScores.Count() == 0) + { + return 0; + } + foreach (var score in studentScores) + { + sum += score.Points; + } + return Math.Round(sum / studentScores.Count(), 1); } // TODO: 使用模式匹配实现成绩等级转换 public Grade GetGrade(double score) { - + return score switch + { + >= 90 => Grade.A, + >= 80 => Grade.B, + >= 70 => Grade.C, + >= 60 => Grade.D, + _ => Grade.F + }; } public List<(string StudentId, double Average)> GetTopStudents(int count) { // TODO: 使用简单循环获取平均分最高的学生 // 提示：可以先计算所有学生的平均分，然后排序取前count个 - + if (count <= 0) + throw new ArgumentException("count必须大于0！"); + + var studentAverages = new List<(string studentId, double average)>(); + foreach (var studentScore in _scores) + { + string id = studentScore.Key; + double avg = CalculateAverage(id); + studentAverages.Add((id, avg)); + } + studentAverages.Sort((a, b) => b.average.CompareTo(a.average)); + var topStudents = new List<(string StudentId, double Average)>(); + for (int i = 0; i < Math.Min(count, studentAverages.Count()); i++) + { + topStudents.Add(studentAverages[i]); + } + return topStudents; } public Dictionary> GetAllScores() { - return new Dictionary>(scores); + return new Dictionary>(_scores); } } @@ -177,7 +259,15 @@ public void SaveStudentsToFile(List students, string filePath) try { // 在这里实现文件写入逻辑 - + using (var writer = new StreamWriter(filePath)) + { + writer.WriteLine("学号,姓名,年龄"); + foreach (var student in students) + { + writer.WriteLine($"{student.StudentId},{student.Name},{student.Age}"); + } + } + Console.WriteLine($"学生信息已保存到 {filePath}"); } catch (Exception ex) { @@ -188,19 +278,55 @@ public void SaveStudentsToFile(List students, string filePath) public List LoadStudentsFromFile(string filePath) { List students = new List(); - + // TODO: 实现从文件读取学生数据 // 提示：使用StreamReader，解析CSV格式 try { // 在这里实现文件读取逻辑 - + if (!File.Exists(filePath)) + { + Console.WriteLine("文件路径不存在！"); + return students; + } + using (var reader = new StreamReader(filePath)) + { + reader.ReadLine(); + string? line; + int count = 0; + while ((line = reader.ReadLine()) != null) + { + count++; + var parts = line.Split(',');//csv格式 + if (parts.Length != 3) + { + Console.WriteLine($"第 {count} 行：\n{line}\n格式错误！已忽略！"); + continue; + } + if (!int.TryParse(parts[2], out int age)) + { + Console.WriteLine($"第 {count} 行：\n{line}\n年龄数据有误！已忽略！"); + continue; + } + + try + { + var student = new Student(parts[0], parts[1], age); + students.Add(student); + } + catch (Exception ex) + { + Console.WriteLine($"第 {count} 行：\n{line}\n创建学生失败！"); + } + } + } + Console.WriteLine($"从 {filePath} 读取到 {students.Count()} 项学生数据"); } catch (Exception ex) { Console.WriteLine($"读取文件时发生错误: {ex.Message}"); } - + return students; } } @@ -230,10 +356,10 @@ static void Main(string[] args) Console.WriteLine("\n2. 添加成绩信息:"); scoreManager.AddScore("2021001", new Score("数学", 95.5)); scoreManager.AddScore("2021001", new Score("英语", 87.0)); - + scoreManager.AddScore("2021002", new Score("数学", 78.5)); scoreManager.AddScore("2021002", new Score("英语", 85.5)); - + scoreManager.AddScore("2021003", new Score("数学", 88.0)); scoreManager.AddScore("2021003", new Score("英语", 92.0)); Console.WriteLine("成绩信息添加完成"); @@ -241,22 +367,50 @@ static void Main(string[] args) // 3. 测试年龄范围查询 Console.WriteLine("\n3. 查找年龄在19-20岁的学生:"); // TODO: 调用GetStudentsByAge方法并显示结果 - + var studentsAged_inRange = studentManager.GetStudentsByAge(19, 20); + Console.WriteLine($"年龄符合要求的学生共有 {studentsAged_inRange.Count()} 位，如下："); + foreach (var student in studentsAged_inRange) + { + Console.WriteLine($"{student}"); + } // 4. 显示学生成绩统计 Console.WriteLine("\n4. 学生成绩统计:"); // TODO: 遍历所有学生，显示其成绩、平均分和等级 - + var allStudents = studentManager.GetAll(); + foreach (var student in allStudents) + { + Console.WriteLine(student.ToString()); + var scores = scoreManager.GetStudentScores(student.StudentId); + foreach (var score in scores) + { + Console.WriteLine($"{score}"); + } + var avg = scoreManager.CalculateAverage(student.StudentId); + var grade = scoreManager.GetGrade(avg); + Console.WriteLine($"平均分：{avg}"); + Console.WriteLine($"等级：{grade}"); + } // 5. 显示排名（简化版） Console.WriteLine("\n5. 平均分最高的学生:"); // TODO: 调用GetTopStudents(1)方法显示第一名 - + var top1_idpair = scoreManager.GetTopStudents(1)[0]; + var top1_student = allStudents.First(stu => stu.StudentId == top1_idpair.StudentId); + Console.WriteLine($"{top1_student}\t平均分：{top1_idpair.Average}"); // 6. 文件操作 Console.WriteLine("\n6. 数据持久化演示:"); // TODO: 保存和读取学生文件 - + dataManager.SaveStudentsToFile(allStudents, "students.csv"); + var loadedStudents = dataManager.LoadStudentsFromFile("students.csv"); + // 显示读取到的学生 + Console.WriteLine("\n从文件加载的学生信息:"); + foreach (var student in loadedStudents) + { + Console.WriteLine($"{student}"); + } + } catch (Exception ex)