LINQ |分类运算符|撤销

在LINQ中，排序运算符用于根据一个或多个属性以升序或降序重新排列给定的序列。 LINQ提供了5种不同类型的排序运算符：

1. 按订单
2. OrderByDescending
3. 然后
4. 然后降序
5. 撤销

反向运算符

反向运算符用于反转序列或集合的顺序。与OrderBy方法不同，它在确定顺序时不考虑自身的实际值，而是以与项目实际显示的相反顺序返回项目。
例如，当您在给定集合上使用“反向方法”时，集合以升序显示，它会反转集合的顺序，即降序排列。

• 它不支持C＃和VB.Net语言的查询语法。
• 它支持C＃和VB.Net语言的方法语法。
• 它同时存在于Queryable和Enumerable类中。
• 它是通过使用延迟执行来实现的。

范例1：

// C# program to reverse the order
// of the given array
using System;
using System.Linq;
  
class GFG {
  
    // Main Method
    static public void Main()
    {
  
        // Data source
        int[] sequence = {1, 2, 3, 4, 5, 6, 7};
  
        // Display the sequence
        Console.WriteLine("The Sequence is: ");
  
        foreach(int s in sequence)
        {
            Console.WriteLine(s);
        }
  
        // Reverse the given array
        // Using Reverse function
        var result = sequence.Reverse();
  
        Console.WriteLine("New Sequence:");
        foreach(var val in result)
        {
            Console.WriteLine(val);
        }
    }
}

输出：

The Sequence is: 
1
2
3
4
5
6
7
New Sequence:
7
6
5
4
3
2
1

范例2：

// C# program to print the 
// name of the employees
using System;
using System.Linq;
using System.Collections.Generic;
  
// Employee details
public class Employee {
  
    public int emp_id
    {
        get;
        set;
    }
  
    public string emp_name
    {
        get;
        set;
    }
  
    public string emp_gender
    {
        get;
        set;
    }
  
    public string emp_hire_date
    {
        get;
        set;
    }
  
    public int emp_salary
    {
        get;
        set;
    }
}
  
public class GFG {
  
    // Main method
    static public void Main()
    {
        List emp = new List() {
  
            new Employee() {emp_id = 209, emp_name = "Anjita", emp_gender = "Female",
                                    emp_hire_date = "12/3/2017", emp_salary = 20000},
  
            new Employee() {emp_id = 210, emp_name = "Soniya", emp_gender = "Female",
                                    emp_hire_date = "22/4/2018", emp_salary = 30000},
  
            new Employee() {emp_id = 211, emp_name = "Rohit", emp_gender = "Male",
                                  emp_hire_date = "3/5/2016", emp_salary = 40000},
  
            new Employee() {emp_id = 212, emp_name = "Supriya", emp_gender = "Female",
                                      emp_hire_date = "4/8/2017", emp_salary = 40000},
  
            new Employee() {emp_id = 213, emp_name = "Anil", emp_gender = "Male",
                                emp_hire_date = "12/1/2016", emp_salary = 40000},
  
            new Employee() {emp_id = 214, emp_name = "Anju", emp_gender = "Female",
                                  emp_hire_date = "17/6/2015", emp_salary = 50000},
        };
  
        // Query to print the name 
        // of the employees using
        // Reverse method
        var res = emp.OrderBy(e => e.emp_name).Reverse();
  
        foreach(var val in res)
        {
            Console.WriteLine("Employee Name: {0}", val.emp_name);
        }
    }
}

输出：

Employee Name: Supriya
Employee Name: Soniya
Employee Name: Rohit
Employee Name: Anju
Employee Name: Anjita
Employee Name: Anil