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CSharp_吕恒语_无41 #19

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164 changes: 134 additions & 30 deletions Homework/Program.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,11 @@ 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
Expand All @@ -20,32 +24,48 @@ public interface IRepository<T>
// Remove(T item) 返回bool
// GetAll() 返回List<T>
// Find(Func<T, bool> predicate) 返回List<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>
{
// TODO: 定义字段 StudentId, Name, Age

public string StudentId;
public string Name;
public int Age;

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）

try{
if(studentId is null) throw new ArgumentNullException("学号不能为空");
if(name is null) throw new ArgumentNullException("姓名不能为空");
if(age==0) throw new ArgumentNullException("年龄不能为0");
}
catch(Exception ex){
Console.WriteLine($"Caught an exception: {ex.Message}");
throw; // 重新抛出异常
}
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 $"Id:{StudentId},Name:{Name},Age:{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)
{

return string.Compare(this.StudentId, other.StudentId, StringComparison.Ordinal);
}

public override bool Equals(object? obj)
Expand All @@ -63,18 +83,27 @@ public override int GetHashCode()
public class Score
{
// TODO: 定义字段 Subject, Points

public string Subject;
public double Points;

public Score(string subject, double points)
{
// TODO: 实现构造方法，包含参数验证

try{
if(subject is null) throw new ArgumentNullException("科目不能为空");
}
catch(Exception ex){
Console.WriteLine($"Caught an exception: {ex.Message}");
throw; // 重新抛出异常
}
Subject=subject;
Points=points;
}

public override string ToString()
{
// TODO: 返回格式化的成绩信息

return $"{Subject}:{Points} ";
}
}

Expand All @@ -83,39 +112,54 @@ public class StudentManager : IRepository<Student>
{
// TODO: 定义私有字段存储学生列表
// 提示：使用List<Student>存储

private List<Student> L=new List<Student>;

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

try{
if(item is null) throw new ArgumentNullException("学生不能为空");
}
catch(Exception ex){
Console.WriteLine($"Caught an exception: {ex.Message}");
throw; // 重新抛出异常
}
L.Add(item);
}

public bool Remove(Student item)
{
// TODO: 实现Remove方法

return L.Remove(item);
}

public List<Student> GetAll()
{
// TODO: 返回学生列表的副本

return new List<Student> _L(L);
}

public List<Student> Find(Func<Student, bool> predicate)
{
// TODO: 使用foreach循环查找符合条件的学生

List<Student> CL=new List<Student>;
foreach(var item in L){
if(predicate(item)) CL.Add(item);
}
return CL;
}

// 查找年龄在指定范围内的学生
public List<Student> GetStudentsByAge(int minAge, int maxAge)
{
// TODO: 使用foreach循环和if判断实现年龄范围查询

List<Student> CL=new List<Student>;
foreach(var item in L){
if(item.Age>=minAge and item.Age<=maxAge) CL.Add(item);
}
return CL;
}
}

Expand All @@ -124,43 +168,63 @@ public class ScoreManager
{
// TODO: 定义私有字段存储成绩字典
// 提示：使用Dictionary<string, List<Score>>存储

private Dictionary<string,List<Score>> D=new Dictionary<string, List<Score>>;

public void AddScore(string studentId, Score score)
{
// TODO: 实现添加成绩的逻辑
// 1. 参数验证
// 2. 初始化学生成绩列表（如不存在）
// 3. 添加成绩

if(studentId is null) throw new ArgumentNullException("学号不能为空");
D[studengId]=new List<Score>();
d[studentId].Add(score);
}

public List<Score> GetStudentScores(string studentId)
{
// TODO: 获取指定学生的所有成绩

return D[studentId];
}

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

double total=0;
int num=0;//科目数
foreach(var item in D[studentId]){
total+=item.Points;
num++;
}
return total/num;
}

// TODO: 使用模式匹配实现成绩等级转换
public Grade GetGrade(double score)
{

Grade degree;
switch(score.Points){
case >=90 :degree=Grade.A;break;
case <90 and >=80 :degree=Grade.B;break;
case <80 and >=70 :degree=Grade.C;break;
case <70 and >=60 :degree=Grade.D;break;
case <60 :degree=Grade.F;
}
return degree;
}

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,double)>;
foreach(var item in D){
averages.Add(item.Key,CalculateAverage(item.Key));
}//计算每个学生的平均分
var topStudents = averages.OrderByDescending(x => x.Average).Take(count).ToList();
return topStudents;
}

public Dictionary<string, List<Score>> GetAllScores()
{
return new Dictionary<string, List<Score>>(scores);
Expand All @@ -177,7 +241,14 @@ public void SaveStudentsToFile(List<Student> students, string filePath)
try
{
// 在这里实现文件写入逻辑

StreamWriter writer=new StreamWriter(filePath);
writer.WriteLine("StudentId,Name,Age,CourseName,ScoreValue");//写入CSV表头
foreach(var item in students){
string escapedName = student.Name.Contains(',') ? $"\"{student.Name}\"" : student.Name;
string escapedCourse = score.CourseName.Contains(',') ? $"\"{score.CourseName}\"" : score.CourseName;
//处理特殊转义字符
writer.WriteLine($"{student.StudentId},{escapedName},{student.Age},{escapedCourse},{score.Value.ToString(CultureInfo.InvariantCulture)}");
}
}
catch (Exception ex)
{
Expand All @@ -194,7 +265,26 @@ public List<Student> LoadStudentsFromFile(string filePath)
try
{
// 在这里实现文件读取逻辑

List<Student> students = new List<Student>();
StreamReader reader=new StreamReader(filePath);
string headerLine = reader.ReadLine();//跳过标题
string line;
while ((line = reader.ReadLine()) != null)
{
var fields = ParseCsvLine(line);// 处理CSV行（考虑字段中包含逗号和引号的情况）
if (fields.Count >= 3) // 至少需要学号、姓名、年龄三个字段
{
string studentId = UnescapeCsvField(fields[0]);
string name = UnescapeCsvField(fields[1]);
int age;
Student student = new Student(studentId, name, age);
students.Add(student);
}
else
{
Console.WriteLine($"警告：跳过格式不正确的行: {line}");
}
}
}
catch (Exception ex)
{
Expand Down Expand Up @@ -241,22 +331,36 @@ 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


int min=19;int max=20;
var studentsBA=studentManager.GetStudentsByAge(min,max);
foreach(var item in studentsBA){
Console.Write($"{item.Name},");
}
// 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

foreach(var item in studentManager.GetAll()){
Console.Write($"{item.Name}:");
foreach(var item1 in scoreManager.GetStudentScores(item.StudentId)){
Consile.Write(item1.ToString());
}//显示格式化成绩信息
Console.Write($"Average:{CalculateAverage(item.StudentId)} ");//显示平均成绩
Console.Write($"Degree:{scoreManager.GetGrade(CalculateAverage(item.StudentId))}");
//显示等级
}

// 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

foreach(var item2 in scoreManager.GetTopStudents(1)){
Console.Write(item2.StudentId);
}

// 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(studentManager.GetAll(), string filePath);
studentManager=new studentManager(dataManager.LoadStudentsFromFile(string filePath));

}
catch (Exception ex)
Expand All @@ -268,4 +372,4 @@ static void Main(string[] args)
Console.ReadKey();
}
}
}
}