9. Generic

using System;
using System.Collections.Generic;
using System.Linq;

class MainClass {
    static void Main() {
        Console.WriteLine("Hello World!");
        
        GenericClass<string> gc1 = new  GenericClass<string>();
        gc1.AddData("Hello");
        Console.WriteLine(gc1.GetData());
        
        var pagedData = new Page<User>(new List<User>());
        
        GenericMethodExample example = new GenericMethodExample();
        example.Display<int>(100);        // Outputs: 100
        example.Display<string>("C#");    // Outputs: C#
        
        // Usage
       IGenericRepository<string> repo = new GenericRepository<string>();
       repo.Add("Item1");
       Console.WriteLine(repo.GetById(0)); // Outputs: Item1
    }
}

public class User {}

public class Page<T>{
    
    public IEnumerable<T> Data {get; set;}
    
    public Page(IEnumerable<T> data){
        Data = data;
    }
}

public class GenericClass<T>{
    
    private T _data;
    
    public T GetData(){
        return _data;
    }
    
    public void AddData(T data){
        _data = data;
    }
    
}

public class GenericMethodExample
{
    public void Display<T>(T data)
    {
        Console.WriteLine(data);
    }
}