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364 changes: 364 additions & 0 deletions Program.cs
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using System;
using System.Collections.Generic;
using System.IO;

namespace StudentManagementSystem
{
// 成绩等级枚举
public enum Grade
{
F = 0,
D = 60,
C = 70,
B = 80,
A = 90
}

// 泛型仓储接口
public interface IRepository<T>
{
void Add(T item);
bool Remove(T item);
List<T> GetAll();
List<T> Find(Func<T, bool> predicate);
}

// 学生类
public class Student : IComparable<Student>
{
public string StudentId { get; private set; }
public string Name { get; private set; }
public int Age { get; private set; }
public Student(string studentId, string name, int age)
{
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) throw new ArgumentOutOfRangeException("年龄不能为负数");

StudentId = studentId;
Name = name;
Age = age;
}
public override string ToString()
{
return $"学号: {StudentId}, 姓名: {Name}, 年龄: {Age}";
}


public int CompareTo(Student? other)
{
if (other == null) return 1; // 如果other为null，当前对象排在前面
return string.Compare(StudentId, other.StudentId, StringComparison.Ordinal);

}

public override bool Equals(object? obj)
{
return obj is Student student && StudentId == student.StudentId;
}
public override int GetHashCode()
{
return StudentId?.GetHashCode() ?? 0;
}
}
// 成绩类
public class Score
{
public string Subject { get; private set; }
public double Points { get; private set; }

public Score(string subject, double points)
{
if (string.IsNullOrWhiteSpace(subject)) throw new ArgumentException("科目不能为空");
if (points < 0 || points > 100) throw new ArgumentOutOfRangeException("成绩必须在0到100之间");
Subject = subject;
Points = points;
}



public override string ToString()
{
return $"科目: {Subject}, 成绩: {Points:F2}"; // 格式化成绩到小数点后两位
}
}

// 学生管理类
public class StudentManager : IRepository<Student>
{
private List<Student> students = new List<Student>();


public void Add(Student item)
{
if (item == null) throw new ArgumentNullException(nameof(item), "学生信息不能为空");
if (students.Contains(item)) throw new InvalidOperationException("学生已存在");
students.Add(item);
students.Sort(); // 保持学生列表按学号排序
}
public bool Remove(Student item)
{
if (item == null) throw new ArgumentNullException(nameof(item), "学生信息不能为空");
if (!students.Contains(item)) throw new InvalidOperationException("学生不存在");
return students.Remove(item);
}
public List<Student> GetAll()
{
return new List<Student>(students);
}
public List<Student> Find(Func<Student, bool> predicate)
{
if (predicate == null) throw new ArgumentNullException(nameof(predicate), "查询条件不能为空");
List<Student> result = new List<Student>();
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<Student> GetStudentsByAge(int minAge, int maxAge)
{
if (minAge < 0 || maxAge < 0) throw new ArgumentOutOfRangeException("年龄不能为负数");
if (minAge > maxAge) throw new ArgumentException("最小年龄不能大于最大年龄");
List<Student> result = new List<Student>();
foreach (var student in students)
{
if (student.Age >= minAge && student.Age <= maxAge)
{
result.Add(student);
}
}
return result;
}
}


// 成绩管理类
public class ScoreManager
{
private Dictionary<string, List<Score>> scores = new Dictionary<string, List<Score>>();
public void AddScore(string studentId, Score score)
{
if (string.IsNullOrWhiteSpace(studentId)) throw new ArgumentException("学号不能为空");
if (score == null) throw new ArgumentNullException(nameof(score), "成绩不能为空");
if (!scores.ContainsKey(studentId))
{
scores[studentId] = new List<Score>();
}
scores[studentId].Add(score);
}

public List<Score> GetStudentScores(string studentId)
{

if (string.IsNullOrWhiteSpace(studentId)) throw new ArgumentException("学号不能为空");
if (scores.ContainsKey(studentId))
{
return new List<Score>(scores[studentId]);
}
return new List<Score>();
}

public double CalculateAverage(string studentId)
{
if (string.IsNullOrWhiteSpace(studentId)) throw new ArgumentException("学号不能为空");
if (!scores.ContainsKey(studentId) || scores[studentId].Count == 0) return 0.0;
double total = 0.0;
int count = 0;
foreach (var score in scores[studentId])
{
total += score.Points;
count++;
}
return total / count;
}

public Grade GetGrade(double score)
{
if (score < 0 || score > 100) throw new ArgumentOutOfRangeException("成绩必须在0到100之间");
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
var averages = new List<(string StudentId, double Average)>();
foreach (var kvp in scores)
{
double avg = CalculateAverage(kvp.Key);
averages.Add((kvp.Key, avg));
}
averages.Sort((a, b) => b.Average.CompareTo(a.Average)); // 按平均分降序排序
return averages.GetRange(0, Math.Min(count, averages.Count));
}

public Dictionary<string, List<Score>> GetAllScores()
{
return new Dictionary<string, List<Score>>(scores);
}
}

// 数据管理类
public class DataManager
{
public void SaveStudentsToFile(List<Student> students, string filePath)
{
// TODO: 实现保存学生数据到文件
// 提示：使用StreamWriter，格式为CSV
try
{// 在这里实现文件写入逻辑
using (var writer = new StreamWriter(filePath))
{
writer.WriteLine("StudentId,Name,Age");
foreach (var student in students)
{
writer.WriteLine($"{student.StudentId},{student.Name},{student.Age}");
}
}
Console.WriteLine("学生数据已保存到文件");
}
catch (Exception ex)
{
Console.WriteLine($"保存文件时发生错误: {ex.Message}");
}
}
public List<Student> LoadStudentsFromFile(string filePath)
{
List<Student> students = new List<Student>();
// 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
using (var reader = new StreamReader(filePath))
{
string headerLine = reader.ReadLine(); // 读取并忽略标题行
string line;
while ((line = reader.ReadLine()) != null)
{
var parts = line.Split(',');
if (parts.Length == 3)
{
string studentId = parts[0];
string name = parts[1];
if (int.TryParse(parts[2], out int age))
{
students.Add(new Student(studentId, name, age));
}
}
}
}
Console.WriteLine("学生数据已从文件加载");
return students;
}
catch (Exception ex)
{
Console.WriteLine($"读取文件时发生错误: {ex.Message}");
}
return students;
}
}

// 主程序
class Program
{
static void Main(string[] args)
{
Console.WriteLine("=== 学生成绩管理系统 ===\n");
// 创建管理器实例
var studentManager = new StudentManager();
var scoreManager = new ScoreManager();
var dataManager = new DataManager();
try
{
// 1. 学生数据（共3个学生）
Console.WriteLine("1. 添加学生信息:");
studentManager.Add(new Student("2021001", "张三", 20));
studentManager.Add(new Student("2021002", "李四", 19));
studentManager.Add(new Student("2021003", "王五", 21));
Console.WriteLine("学生信息添加完成");

// 2. 成绩数据（每个学生各2门课程）
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");

// 3. 测试年龄范围查询
Console.WriteLine("\n3. 查找年龄在19-20岁的学生:");
var ageFilteredStudents = studentManager.GetStudentsByAge(19, 20);
foreach (var student in ageFilteredStudents)
{
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)
{
var scores = scoreManager.GetStudentScores(student.StudentId);
double average = scoreManager.CalculateAverage(student.StudentId);
Grade grade = scoreManager.GetGrade(average);
Console.WriteLine($"\n学生: {student}");
Console.WriteLine("成绩:");
foreach (var score in scores)
{
Console.WriteLine($" {score}");
}
Console.WriteLine($"平均分: {average:F2}, 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 topStudents = scoreManager.GetTopStudents(1);
foreach (var (StudentId, Average) in topStudents)
{
var student = allStudents.Find(s => s.StudentId == StudentId);
if (student != null)
{
Console.WriteLine($"第一名: {student}, 平均分: {Average:F2}");
}
}

// 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
string filePath = "students.csv";
dataManager.SaveStudentsToFile(allStudents, filePath);
var loadedStudents = dataManager.LoadStudentsFromFile(filePath);
Console.WriteLine("从文件加载的学生信息:");
foreach (var student in loadedStudents)
{
Console.WriteLine(student);
}
}
catch (Exception ex)
{
Console.WriteLine($"程序执行过程中发生错误: {ex.Message}");
}
Console.WriteLine("\n程序执行完毕，按任意键退出...");
Console.ReadKey();
}
}
}