LINQ |分区运算符|跳过
原文:https://www.geeksforgeeks.org/linq-partition-operator-skip/
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
跳过运算符
Skip 运算符用于将元素向上跳过到给定序列或集合中的指定位置。或者换句话说，我们可以说它跳过了指定数量的元素，并返回给定集合或序列中存在的剩余元素。
- 它不支持 C# 和 VB.Net 语言中的查询语法。但是您可以使用 Skip 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 Skip 方法。
- 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。
- 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 Skip operator
using System;
using System.Linq;
class GFG {
static public void Main()
{
// Data source
char[] sequence1 = {'c', 'y', 'p',
'q', 'l', 'a'};
int[] sequence2 = {202, 2002, 20002,
200002, 2000002};
// Display the sequences
Console.WriteLine("Original Sequence 1 is: ");
foreach(var s1 in sequence1)
{
Console.WriteLine(s1);
}
// Query which skips starting 4
// elements of the sequence1
// Using Skip method
var result1 = sequence1.Skip(4);
Console.WriteLine("New Sequence: ");
// Display new sequence
foreach(var val in result1)
{
Console.WriteLine(val);
}
Console.WriteLine("Original Sequence 2 is: ");
foreach(var s2 in sequence2)
{
Console.WriteLine(s2);
}
// Query which skip starting 2
// elements of the sequence2
// Using Skip method
var result2 = sequence2.Skip(2);
Console.WriteLine("New Sequence: ");
// Display new sequence
foreach(var val in result2)
{
Console.WriteLine(val);
}
}
}
Output:
Original Sequence 1 is:
c
y
p
q
l
a
New Sequence:
l
a
Original Sequence 2 is:
202
2002
20002
200002
2000002
New Sequence:
20002
200002
2000002
例 2:
// C# program to find the Id's of
// the employees starting from 211
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 = "Supriya", 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 Id's of
// the employees starting from 211
// Using Skip method
var res = (from e in emp
select e.emp_id)
.Skip(2);
foreach(var val in res)
{
Console.WriteLine("Employee Id: {0}", val);
}
}
}
Output:
Employee Id: 211
Employee Id: 212
Employee Id: 213
Employee Id: 214
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