C# Online Compiler | .NET Fiddle

<no name> by Anonymous

using System;
using System.IO;
using System.Collections.Generic;
using Newtonsoft.Json;
					
public class Program
{
	public static void Main()
	{
		// ===================================================================
		// Example 1: Create data source and manager objects
		// ===================================================================
		
		//var dataSource = new JsonFileStudentDataSource("students.json");
		var dataSource = new InMemoryStudentDataSource();
		var manager = new StudentManager(dataSource);
		
		var students = manager.GetStudents();
		
		DumpStudentList("All students:", students);
		
		// ===================================================================
		// Example 2: Insert new student and save
		// ===================================================================
		
		var newStudent = new Student()
		{ 
			Id = "2012710", 
			FullName = "Phan Thanh Thao", 
			Dob = new DateTime(2011, 4, 21), 
			Gender = "Female", 
			ClassName = "CTK44", 
			Subjects = new List<string>() 
			{ 
				"Do hoa may tinh", 
				"Nhap mon nganh CNTT", 
				"Giao duc the chat" 
			}
		};
		manager.Add(newStudent);
		
		DumpStudentList("After inserting new student:", students);
				
		// ===================================================================
		// Example 3: Delete a student by id
		// ===================================================================
		
		if (manager.DeleteById("2012517"))
		{
			Console.WriteLine("Student 2012517 has been deleted");
		}
		else
		{
			Console.WriteLine("Could not find student 2012517");
		}
		
		Console.WriteLine();
		
		// ===================================================================
		// Example 4: Search students by name using interface
		// ===================================================================
		
		var filterCondition = new StudentNameFilter("van");
		var vanStudents = manager.Find(filterCondition);
		
		DumpStudentList("Filter by name containing 'van':", vanStudents);
		
		// ===================================================================
		// Example 5: Search students with complex condition using interface
		// ===================================================================
		
		var filterParam = new StudentQuery()
		{
			Age = 8,
			Subject = "HE DIEU HANH",
			ClassName = "ctk40"
		};
		var complexCondition = new StudentComplexFilter(filterParam);
		var studentSet = manager.Find(complexCondition);
		
		DumpStudentList("Filter by complicated conditions:", studentSet);
		
		// ===================================================================
		// Example 6: Search students by gender using built-in delegate
		// ===================================================================
		
		Predicate<Student> matchFunc = delegate (Student sv)
		{
			return sv.Gender == "Female";
		};
		
		var femaleStudents = manager.Find(matchFunc);
		
		DumpStudentList("Filter by gender = Female:", femaleStudents);
	}
	
	static void DumpStudentList(string title, List<Student> students)
	{
		Console.WriteLine(title);
		Console.WriteLine();
		
		Console.WriteLine("{0,-10}{1,-30}{2,-12:dd/MM/yyyy}{3,-10}{4,-10}{5,10}", 
			"MSSV", "Ho va Ten", "Ngay sinh", "Gioi tinh", "Lop", "So mon hoc");
		
		Console.WriteLine("{0,-10}{1,-30}{2,-12:dd/MM/yyyy}{3,-10}{4,-10}{5,10}", 
			"---------", "-----------------------------", "-----------", "---------", "---------", "----------");
		
		foreach (var item in students)
		{
			Console.WriteLine("{0,-10}{1,-30}{2,-12:dd/MM/yyyy}{3,-10}{4,-10}{5,10}", 
							  item.Id, item.FullName, item.Dob, item.Gender, item.ClassName, item.Subjects.Count);
		}
	
		Console.WriteLine("{0,-10}{1,-30}{2,-12:dd/MM/yyyy}{3,-10}{4,-10}{5,10}", 
			"---------", "-----------------------------", "-----------", "---------", "---------", "----------");
		
		Console.WriteLine();
	}
}

public class Student
{
	public string Id { get; set; }
	public string FullName { get; set; }
	public DateTime Dob { get; set; }
	public string Gender { get; set; }
	public string ClassName { get; set; }
	public List<string> Subjects { get; set; }
}

public class StudentManager
{
	private IStudentDataSource _dataSource;
	private List<Student> _studentList;	
	
	public StudentManager(IStudentDataSource dataSource)
	{
		if (dataSource == null)
			throw new ArgumentNullException("dataSource");
		
		_dataSource = dataSource;
		_studentList = _dataSource.GetStudents();
	}
	
	public List<Student> GetStudents(bool forceReload = false)
	{
		if (forceReload)
		{
			_studentList = _dataSource.GetStudents();
		}
			
		return _studentList;
	}
	
	public Student FindById(string id)
	{
		foreach (var item in _studentList)
		{
			if (item.Id == id) return item;
		}
		
		return null;
	}
	
	public int Find(Student student)
	{
		for (var idx = 0; idx < _studentList.Count; idx++)
		{
			if (_studentList[idx].Id == student.Id)
				return idx;
		}
		
		return -1;
	}
	
	public List<Student> Find(IStudentFilter condition)
	{
		var results = new List<Student>();
		
		foreach (var item in _studentList)
		{
			if (condition.IsMatch(item))
				results.Add(item);
		}
		
		return results;
	}
	
	public List<Student> Find(Predicate<Student> matchFunc)
	{
		var results = new List<Student>();
		
		foreach (var item in _studentList)
		{
			if (matchFunc(item))
				results.Add(item);
		}
		
		return results;
	}
	
	public bool Add(Student student)
	{
		if (FindById(student.Id) != null)
			return false;
		
		_studentList.Add(student);
		_dataSource.Save(_studentList);
		
		return true;
	}
	
	public void AddOrUpdate(Student student)
	{
		var idx = Find(student);
		
		if (idx < 0)
		{
			Add(student);
		}
		else
		{
			_studentList[idx] = student;
			_dataSource.Save(_studentList);
		}
	}
	
	public bool DeleteById(string id)
	{
		var student = FindById(id);
		if (student == null) return false;
		
		Delete(student);
		return true;
	}
	
	public void Delete(Student student)
	{
		_studentList.Remove(student);
		_dataSource.Save(_studentList);
	}
	
	public void CreateFakeData()
	{
		var students = new List<Student>()
		{
			new Student() { Id = "2012345", FullName = "Nguyen Van Thanh Phong", Dob = new DateTime(2012, 6, 16), Gender = "Male", ClassName = "CTK44", Subjects = new List<string>() { "He dieu hanh", "Tin hoc co so" }},
			new Student() { Id = "2012346", FullName = "Nguyen Van Thanh Son", Dob = new DateTime(2015, 8, 29), Gender = "Male", ClassName = "CTK44", Subjects = new List<string>() { "Lap trinh cau truc", "Tin hoc co so", "Toan cao cap" }},
			new Student() { Id = "2012517", FullName = "Nguyen Thi Thao Nguyen", Dob = new DateTime(2014, 9, 11), Gender = "Female", ClassName = "CTK44", Subjects = new List<string>() { "Lap trinh Web", "Nhap mon nganh CNTT", "Giao duc the chat" }},
		};
		
		_dataSource.Save(students);
	}
}

public interface IStudentDataSource
{
	List<Student> GetStudents();
	
	void Save(List<Student> students);
}

public class JsonFileStudentDataSource : IStudentDataSource
{
	private string _filePath;

	public JsonFileStudentDataSource(string filePath)
	{
		_filePath = filePath;
	}

	public List<Student> GetStudents()
	{
		if (!File.Exists(_filePath))
		{
			return new List<Student>();
		}
	
		var jsonData = File.ReadAllText(_filePath);
		return JsonConvert.DeserializeObject<List<Student>>(jsonData);
	}
	
	public void Save(List<Student> students)
	{
		var jsonData = JsonConvert.SerializeObject(students);
		File.WriteAllText(_filePath, jsonData);
	}
}

public class InMemoryStudentDataSource : IStudentDataSource
{
	private List<Student> _students;

	public InMemoryStudentDataSource()
	{
		_students = new List<Student>()
		{
			new Student() { Id = "2012345", FullName = "Nguyen Van Thanh Phong", Dob = new DateTime(2012, 6, 16), Gender = "Male", ClassName = "CTK40", Subjects = new List<string>() { "He dieu hanh", "Tin hoc co so" }},
			new Student() { Id = "2012346", FullName = "Nguyen Van Thanh Son", Dob = new DateTime(2015, 8, 29), Gender = "Male", ClassName = "CTK44", Subjects = new List<string>() { "Lap trinh cau truc", "Tin hoc co so", "Toan cao cap" }},
			new Student() { Id = "2012517", FullName = "Nguyen Thi Thao Nguyen", Dob = new DateTime(2014, 9, 11), Gender = "Female", ClassName = "CTK43", Subjects = new List<string>() { "Lap trinh Web", "Nhap mon nganh CNTT", "Giao duc the chat" }},
			new Student() { Id = "2012890", FullName = "Tran Thi Bich Thuy", Dob = new DateTime(2012, 9, 11), Gender = "Female", ClassName = "CTK40", Subjects = new List<string>() { "He dieu hanh", "Nhap mon nganh CNTT", "Giao duc the chat" }}
		};
	}

	public List<Student> GetStudents()
	{
		return _students;
	}
	
	public void Save(List<Student> students)
	{
		_students = students;
	}
}

public interface IStudentFilter
{
	bool IsMatch(Student student);
}

public class StudentNameFilter : IStudentFilter
{
	private string _keyword;
	
	public StudentNameFilter(string name)
	{
		if (name != null)
		{
			_keyword = name.ToLower();
		}
	}

	public bool IsMatch(Student student)
	{
		if (string.IsNullOrWhiteSpace(_keyword))
			return true;
	
		return student.FullName.ToLower().Contains(_keyword);
	}
}

public class StudentComplexFilter : IStudentFilter
{
	private StudentQuery _condition;
	
	public StudentComplexFilter(StudentQuery condition)
	{
		_condition = condition;
	}

	public bool IsMatch(Student student)
	{
		var matched = true;
	
		if (!string.IsNullOrWhiteSpace(_condition.Name))
		{
			var name = _condition.Name.ToLower();
			matched &= student.FullName.ToLower().Contains(name);
		}
		
		if (!string.IsNullOrWhiteSpace(_condition.Gender))
		{
			matched &= student.Gender.Equals(_condition.Gender, StringComparison.InvariantCultureIgnoreCase);
		}
		
		if (_condition.Age != null)
		{
			var age = DateTime.Today.Year - student.Dob.Year;
			matched &= age == _condition.Age.Value;
		}
		
		if (!string.IsNullOrWhiteSpace(_condition.ClassName))
		{
			matched &= student.ClassName.Equals(_condition.ClassName, StringComparison.InvariantCultureIgnoreCase);
		}
		
		if (!string.IsNullOrWhiteSpace(_condition.Subject))
		{
			var found = false;
			
			foreach (var subjectName in student.Subjects)
			{
				if (subjectName.Equals(_condition.Subject, StringComparison.InvariantCultureIgnoreCase))
				{
					found = true;
					break;
				}
			}
			
			matched &= found;
		}
	
		return matched;
	}
}

public class StudentQuery
{
	public string Name { get; set; }
	public string Gender { get; set; }
	public int? Age { get; set; }
	public string ClassName { get; set; }
	public string Subject { get; set; }
}

​x
 
using System;
using System.IO;
using System.Collections.Generic;
using Newtonsoft.Json;
                    
public class Program
{
    public static void Main()
    {
        // ===================================================================
        // Example 1: Create data source and manager objects
        // ===================================================================
        
        //var dataSource = new JsonFileStudentDataSource("students.json");
        var dataSource = new InMemoryStudentDataSource();
        var manager = new StudentManager(dataSource);
        
        var students = manager.GetStudents();
        
        DumpStudentList("All students:", students);
        
        // ===================================================================
        // Example 2: Insert new student and save
        // ===================================================================
        
        var newStudent = new Student()
        { 
            Id = "2012710", 
            FullName = "Phan Thanh Thao", 
            Dob = new DateTime(2011, 4, 21), 
            Gender = "Female", 
            ClassName = "CTK44", 
            Subjects = new List<string>() 
            { 
                "Do hoa may tinh", 
                "Nhap mon nganh CNTT", 
                "Giao duc the chat" 
            }
        };
        manager.Add(newStudent);
        
        DumpStudentList("After inserting new student:", students);
                
        // ===================================================================
        // Example 3: Delete a student by id
        // ===================================================================
        
        if (manager.DeleteById("2012517"))
        {
            Console.WriteLine("Student 2012517 has been deleted");
        }
        else
        {
            Console.WriteLine("Could not find student 2012517");
        }
        
        Console.WriteLine();
        
        // ===================================================================
        // Example 4: Search students by name using interface
        // ===================================================================
        
        var filterCondition = new StudentNameFilter("van");
        var vanStudents = manager.Find(filterCondition);
        
        DumpStudentList("Filter by name containing 'van':", vanStudents);
        
        // ===================================================================
        // Example 5: Search students with complex condition using interface
        // ===================================================================
        
        var filterParam = new StudentQuery()
        {
            Age = 8,
            Subject = "HE DIEU HANH",
            ClassName = "ctk40"
        };
        var complexCondition = new StudentComplexFilter(filterParam);
        var studentSet = manager.Find(complexCondition);
        
        DumpStudentList("Filter by complicated conditions:", studentSet);
        
        // ===================================================================
        // Example 6: Search students by gender using built-in delegate
        // ===================================================================
        
        Predicate<Student> matchFunc = delegate (Student sv)
        {
            return sv.Gender == "Female";
        };
        
        var femaleStudents = manager.Find(matchFunc);
        
        DumpStudentList("Filter by gender = Female:", femaleStudents);
    }
    
    static void DumpStudentList(string title, List<Student> students)
    {
        Console.WriteLine(title);
        Console.WriteLine();
        
        Console.WriteLine("{0,-10}{1,-30}{2,-12:dd/MM/yyyy}{3,-10}{4,-10}{5,10}", 
            "MSSV", "Ho va Ten", "Ngay sinh", "Gioi tinh", "Lop", "So mon hoc");
        
        Console.WriteLine("{0,-10}{1,-30}{2,-12:dd/MM/yyyy}{3,-10}{4,-10}{5,10}", 
            "---------", "-----------------------------", "-----------", "---------", "---------", "----------");
        
        foreach (var item in students)
        {
            Console.WriteLine("{0,-10}{1,-30}{2,-12:dd/MM/yyyy}{3,-10}{4,-10}{5,10}", 
                              item.Id, item.FullName, item.Dob, item.Gender, item.ClassName, item.Subjects.Count);
        }
    
        Console.WriteLine("{0,-10}{1,-30}{2,-12:dd/MM/yyyy}{3,-10}{4,-10}{5,10}", 
            "---------", "-----------------------------", "-----------", "---------", "---------", "----------");
        
        Console.WriteLine();
    }
}
​
public class Student
{
    public string Id { get; set; }
    public string FullName { get; set; }
    public DateTime Dob { get; set; }
    public string Gender { get; set; }
    public string ClassName { get; set; }
    public List<string> Subjects { get; set; }
}
​
public class StudentManager
{
    private IStudentDataSource _dataSource;
    private List<Student> _studentList; 
    
    public StudentManager(IStudentDataSource dataSource)
    {
        if (dataSource == null)
            throw new ArgumentNullException("dataSource");
        
        _dataSource = dataSource;
        _studentList = _dataSource.GetStudents();
    }
    
    public List<Student> GetStudents(bool forceReload = false)
    {
        if (forceReload)
        {
            _studentList = _dataSource.GetStudents();
        }
            
        return _studentList;
    }
    
    public Student FindById(string id)
    {
        foreach (var item in _studentList)
        {
            if (item.Id == id) return item;
        }
        
        return null;
    }
    
    public int Find(Student student)
    {
        for (var idx = 0; idx < _studentList.Count; idx++)
        {
            if (_studentList[idx].Id == student.Id)
                return idx;
        }
        
        return -1;
    }
    
    public List<Student> Find(IStudentFilter condition)
    {
        var results = new List<Student>();
        
        foreach (var item in _studentList)
        {
            if (condition.IsMatch(item))
                results.Add(item);
        }
        
        return results;
    }
    
    public List<Student> Find(Predicate<Student> matchFunc)
    {
        var results = new List<Student>();
        
        foreach (var item in _studentList)
        {
            if (matchFunc(item))
                results.Add(item);
        }
        
        return results;
    }
    
    public bool Add(Student student)
    {
        if (FindById(student.Id) != null)
            return false;
        
        _studentList.Add(student);
        _dataSource.Save(_studentList);
        
        return true;
    }
    
    public void AddOrUpdate(Student student)
    {
        var idx = Find(student);
        
        if (idx < 0)
        {
            Add(student);
        }
        else
        {
            _studentList[idx] = student;
            _dataSource.Save(_studentList);
        }
    }
    
    public bool DeleteById(string id)
    {
        var student = FindById(id);
        if (student == null) return false;
        
        Delete(student);
        return true;
    }
    
    public void Delete(Student student)
    {
        _studentList.Remove(student);
        _dataSource.Save(_studentList);
    }
    
    public void CreateFakeData()
    {
        var students = new List<Student>()
        {
            new Student() { Id = "2012345", FullName = "Nguyen Van Thanh Phong", Dob = new DateTime(2012, 6, 16), Gender = "Male", ClassName = "CTK44", Subjects = new List<string>() { "He dieu hanh", "Tin hoc co so" }},
            new Student() { Id = "2012346", FullName = "Nguyen Van Thanh Son", Dob = new DateTime(2015, 8, 29), Gender = "Male", ClassName = "CTK44", Subjects = new List<string>() { "Lap trinh cau truc", "Tin hoc co so", "Toan cao cap" }},
            new Student() { Id = "2012517", FullName = "Nguyen Thi Thao Nguyen", Dob = new DateTime(2014, 9, 11), Gender = "Female", ClassName = "CTK44", Subjects = new List<string>() { "Lap trinh Web", "Nhap mon nganh CNTT", "Giao duc the chat" }},
        };
        
        _dataSource.Save(students);
    }
}
​
public interface IStudentDataSource
{
    List<Student> GetStudents();
    
    void Save(List<Student> students);
}
​
public class JsonFileStudentDataSource : IStudentDataSource
{
    private string _filePath;
​
    public JsonFileStudentDataSource(string filePath)
    {
        _filePath = filePath;
    }
​
    public List<Student> GetStudents()
    {
        if (!File.Exists(_filePath))
        {
            return new List<Student>();
        }
    
        var jsonData = File.ReadAllText(_filePath);
        return JsonConvert.DeserializeObject<List<Student>>(jsonData);
    }
    
    public void Save(List<Student> students)
    {
        var jsonData = JsonConvert.SerializeObject(students);
        File.WriteAllText(_filePath, jsonData);
    }
}
​
public class InMemoryStudentDataSource : IStudentDataSource
{
    private List<Student> _students;
​
    public InMemoryStudentDataSource()
    {
        _students = new List<Student>()
        {
            new Student() { Id = "2012345", FullName = "Nguyen Van Thanh Phong", Dob = new DateTime(2012, 6, 16), Gender = "Male", ClassName = "CTK40", Subjects = new List<string>() { "He dieu hanh", "Tin hoc co so" }},
            new Student() { Id = "2012346", FullName = "Nguyen Van Thanh Son", Dob = new DateTime(2015, 8, 29), Gender = "Male", ClassName = "CTK44", Subjects = new List<string>() { "Lap trinh cau truc", "Tin hoc co so", "Toan cao cap" }},
            new Student() { Id = "2012517", FullName = "Nguyen Thi Thao Nguyen", Dob = new DateTime(2014, 9, 11), Gender = "Female", ClassName = "CTK43", Subjects = new List<string>() { "Lap trinh Web", "Nhap mon nganh CNTT", "Giao duc the chat" }},
            new Student() { Id = "2012890", FullName = "Tran Thi Bich Thuy", Dob = new DateTime(2012, 9, 11), Gender = "Female", ClassName = "CTK40", Subjects = new List<string>() { "He dieu hanh", "Nhap mon nganh CNTT", "Giao duc the chat" }}
        };
    }
​
    public List<Student> GetStudents()
    {
        return _students;
    }
    
    public void Save(List<Student> students)
    {
        _students = students;
    }
}
​
public interface IStudentFilter
{
    bool IsMatch(Student student);
}
​
public class StudentNameFilter : IStudentFilter
{
    private string _keyword;
    
    public StudentNameFilter(string name)
    {
        if (name != null)
        {
            _keyword = name.ToLower();
        }
    }
​
    public bool IsMatch(Student student)
    {
        if (string.IsNullOrWhiteSpace(_keyword))
            return true;
    
        return student.FullName.ToLower().Contains(_keyword);
    }
}
​
public class StudentComplexFilter : IStudentFilter
{
    private StudentQuery _condition;
    
    public StudentComplexFilter(StudentQuery condition)
    {
        _condition = condition;
    }
​
    public bool IsMatch(Student student)
    {
        var matched = true;
    
        if (!string.IsNullOrWhiteSpace(_condition.Name))
        {
            var name = _condition.Name.ToLower();
            matched &= student.FullName.ToLower().Contains(name);
        }
        
        if (!string.IsNullOrWhiteSpace(_condition.Gender))
        {
            matched &= student.Gender.Equals(_condition.Gender, StringComparison.InvariantCultureIgnoreCase);
        }
        
        if (_condition.Age != null)
        {
            var age = DateTime.Today.Year - student.Dob.Year;
            matched &= age == _condition.Age.Value;
        }
        
        if (!string.IsNullOrWhiteSpace(_condition.ClassName))
        {
            matched &= student.ClassName.Equals(_condition.ClassName, StringComparison.InvariantCultureIgnoreCase);
        }
        
        if (!string.IsNullOrWhiteSpace(_condition.Subject))
        {
            var found = false;
            
            foreach (var subjectName in student.Subjects)
            {
                if (subjectName.Equals(_condition.Subject, StringComparison.InvariantCultureIgnoreCase))
                {
                    found = true;
                    break;
                }
            }
            
            matched &= found;
        }
    
        return matched;
    }
}
​
public class StudentQuery
{
    public string Name { get; set; }
    public string Gender { get; set; }
    public int? Age { get; set; }
    public string ClassName { get; set; }
    public string Subject { get; set; }
}

Compilation error (line 1, col 1): A namespace cannot directly contain members such as fields or methods

Last Run:	12:44:27 am
Compile:	0s
Execute:	0.031s
Memory:	0b
CPU:	0s

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