LINQ |量词运算符|全部

在LINQ中，量词运算符用于返回一个布尔值，该值表明是否某些或所有元素都满足给定条件。标准查询运算符支持3种不同类型的量词运算符：

1. 全部
2. 任何
3. 包含

所有操作员

All运算符用于检查序列中的每个元素，如果所有元素都满足给定条件，则它将返回true。否则，返回false。例如，我们有一个序列，即aa，aa，aa，aa 。为了检查序列中的所有元素是否都是“ aa ”，我们使用All运算符，该运算符检查给定序列中存在的每个元素，并返回true，因为给定序列中存在的所有元素都满足给定条件。

重要事项：

• 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。
• 如果给定的源或条件为null，它将抛出ArgumentNullException 。
• 它不返回值，而是返回true或false。
• 该运算符的返回类型为System.Boolean 。

范例1：

// C# program to illustrate the
// use of All operator
using System;
using System.Linq;
using System.Collections.Generic;
  
class GFG {
  
    static public void Main()
    {
  
        // Data source
        int[] sequence1 = {112, 44, 55, 66,
                              77, 777, 56};
                                
        string[] sequence2 = {"aa", "aa", "aa",
                             "aa", "aa", "aa"};
  
        // Check the sequence1 contain
        // all element as 77
        // Using All operator
        var result1 = sequence1.All(seq => seq == 77);
  
        Console.WriteLine("Is the given sequence contain"+
                     " all element as 77 : {0}", result1);
  
        // Check the sequence2 contain
        // all element as aa
        // Using All operator
        var result2 = sequence2.All(seq => seq == "aa");
  
        Console.WriteLine("Is the given sequence contain"+
                   " all element as 'aa' : {0}", result2);
    }
}

输出：

Is the given sequence contain all element as 77 : False
Is the given sequence contain all element as 'aa' : True

范例2：

// C# program to check in the employee present
// in the company are all female employee
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 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 check in the employee present
        // in the company are all female employee
        // Using All method
        var res = emp.All(e => e.emp_gender == "Female");
          
        Console.WriteLine("Is all the employees are female?: {0}", res);
    }
}

输出：

Is all the employees are female?: False