LINQ |分区运算符|跳过

在LINQ中，分区运算符用于将给定序列分为两部分，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：

1. 跳过
2. 跳过而
3. 拿
4. 边走边走

跳过运算符

跳过运算符用于将元素跳过到给定序列或集合中的指定位置。换句话说，我们可以说它跳过指定数量的元素，并返回给定集合或序列中存在的其余元素。

• 它不支持C＃和VB.Net语言的查询语法。但是您可以使用Skip方法查询变量，也可以将查询括在方括号中，然后调用Skip方法。
• 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。
• 如果源为null，它将抛出ArgumentNullException。

范例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);
        }
    }
}

输出：

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

范例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 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 = 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);
        }
    }
}

输出：

Employee Id: 211
Employee Id: 212
Employee Id: 213
Employee Id: 214