LINQ |分区符|取
原文:https://www.geeksforgeeks.org/linq-partition-operator-take/
在 LINQ，分区运算符用于将给定的序列分成两部分，而无需对元素进行排序，并返回其中一部分。标准查询运算符支持 4 种不同类型的分区运算符:
- 跳过
- 滑行同时
- 取
- 趁
带操作员
Take 运算符用于从序列开始返回指定数量的相邻元素。或者换句话说，我们可以说它从第一个项目开始返回指定数量的项目。如下例所示:
要点:
- 它不支持 C# 和 VB.Net 语言中的查询语法。但是您可以使用 Take 方法来查询变量，或者您可以将查询包装在括号中，然后调用 Take 方法。如例 2 所示。
- 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。
- 它通过使用延迟执行来实现。
- 如果源为空，它将引发 ArgumentNullException。
例 1:
// C# program to illustrate the
// concept of Taking operator
using System;
using System.Linq;
class GFG {
// Main Method
static public void Main()
{
// Data source
int[] sequence = {45, 67, 89,
13, 56, 76, 67};
// Query which picks starting 5 ordered
// elements from the given sequence
// Using Take method
var result = sequence.OrderBy(s => s).Take(5);
Console.WriteLine("New Sequence: ");
// Display new sequence
foreach(var val in result)
{
Console.WriteLine(val);
}
}
}
Output:
New Sequence:
13
45
56
67
67
例 2:
// C# program to find the names
// of the first 4 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<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 = "Anu", emp_gender = "Female",
emp_hire_date = "4/8/2017", emp_salary = 80000},
new Employee() {emp_id = 213, emp_name = "Anil", emp_gender = "Male",
emp_hire_date = "12/1/2016", emp_salary = 60000},
new Employee() {emp_id = 214, emp_name = "Anju", emp_gender = "Female",
emp_hire_date = "17/6/2015", emp_salary = 50000},
};
// Query to find the names
// of the first 4 employees
// Using Take method
var res = (from e in emp
select e.emp_name)
.Take(4);
foreach(var val in res)
{
Console.WriteLine("Employee Name: {0}", val);
}
}
}
Output:
Employee Name: Anjita
Employee Name: Soniya
Employee Name: Rohit
Employee Name: Anu
版权属于：月萌API www.moonapi.com，转载请注明出处
