LINQ |分拣员|然后是
原文:https://www.geeksforgeeks.org/linq-sorting-operator-thenby/
在 LINQ，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 有 5 种不同类型的分拣操作员:
- 排序依据
- 按降序排序
- 然后通过
- 然后下降
- 反转
然后按运算符
ThenBy 运算符用于实现升序的二级排序。运算符支持多重排序。通常，排序方法与排序方法一起使用。 OrderBy()方法，首先对序列或集合的元素进行升序排序，然后使用 By()方法再次对 OrderBy()方法的结果进行升序排序。或者换句话说，在 LINQ，集合是按照 OrderBy 方法给出的主字段进行的第一次排序，之后主排序的结果再次按照 ThenBy 方法给出的次字段进行排序。
- 它不支持 C# 和 VB.Net 语言中的查询语法。
- 它支持 C# 和 VB.Net 语言中方法语法。
- 它同时出现在可查询类和可枚举类中。
- 查询语法中的二级排序是用逗号分隔的，如示例 1 所示。
- 它通过使用延迟执行来实现。
例 1:
// C# program to print the employees
// names and their gender in the
// ascending order
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;
}
}
class GFG {
// Main method
static public void Main()
{
List<Employee> emp = new List<Employee>() {
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 and
// gender of the employees in
// ascending order In query syntax
var res = from e in emp
orderby e.emp_name, e.emp_gender
select e;
foreach(var val in res)
{
Console.WriteLine("Employee Name: {0} Gender: {1}",
val.emp_name, val.emp_gender);
}
}
}
Output:
Employee Name: Anil Gender: Male
Employee Name: Anjita Gender: Female
Employee Name: Anju Gender: Female
Employee Name: Rohit Gender: Male
Employee Name: Soniya Gender: Female
Employee Name: Supriya Gender: Female
例 2:
// C# program to print the employees
// names and their salary in the
// ascending order
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;
}
}
class GFG {
// Main method
static public void Main()
{
List<Employee> emp = new List<Employee>() {
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 and
// salary of the employees in
// ascending order Using OrderBy
// and ThenBy method
var res = emp.OrderBy(e => e.emp_name).ThenBy(e => e.emp_salary);
foreach(var val in res)
{
Console.WriteLine("Employee Name: {0} Salary: {1}",
val.emp_name, val.emp_salary);
}
}
}
Output:
Employee Name: Anil Salary: 40000
Employee Name: Anjita Salary: 20000
Employee Name: Anju Salary: 50000
Employee Name: Rohit Salary: 40000
Employee Name: Soniya Salary: 30000
Employee Name: Supriya Salary: 40000
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