C#中LINQ to Objects查询的实现

var result = from person in people
             where person.Age > 18
             select person.Name;

var result = people.Where(person => person.Age > 18)
                   .Select(person => person.Name);

var sortedPeople = people.OrderBy(person => person.Age);

var groupedPeople = people.GroupBy(person => person.Department);

var totalAge = people.Sum(person => person.Age);
var averageAge = people.Average(person => person.Age);
var personCount = people.Count();

using System;
using System.Collections.Generic;
using System.Linq;
class Person
{
    public string Name { get; set; }
    public int Age { get; set; }
    public string Department { get; set; }
}
class Program
{
    static void Main(string[] args)
    {
        List<Person> people = new List<Person>
        {
            new Person { Name = "Alice", Age = 25, Department = "HR" },
            new Person { Name = "Bob", Age = 30, Department = "IT" },
            new Person { Name = "Carol", Age = 22, Department = "IT" },
            new Person { Name = "David", Age = 28, Department = "HR" }
        };
        var itEmployees = from person in people
                          where person.Department == "IT"
                          select person.Name;
        var averageAge = people.Average(person => person.Age);
        var groupedPeople = from person in people
                            group person by person.Department;
        Console.WriteLine("IT Employees:");
        foreach (var employeeName in itEmployees)
        {
            Console.WriteLine(employeeName);
        }
        Console.WriteLine("Average age: " + averageAge);
        Console.WriteLine("Grouped People:");
        foreach (var group in groupedPeople)
        {
            Console.WriteLine($"{group.Key}: {group.Count()} people");
        }
    }
}