Enumerable.Any 方法

定义

命名空间:: System.Linq

程序集:: System.Core.dll, System.Linq.dll

程序集:: netstandard.dll, System.Linq.dll

程序集:: System.Linq.dll

程序集:: System.Core.dll

程序集:: netstandard.dll

重要

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确定序列的任何元素是否存在或满足条件。

重载

名称	说明
Any<TSource>(IEnumerable<TSource>)	确定序列是否包含任何元素。
Any<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)	确定序列的任何元素是否满足条件。

Any<TSource>(IEnumerable<TSource>)

Source:: AnyAll.cs

Source:: AnyAll.cs

Source:: AnyAll.cs

Source:: AnyAll.cs

Source:: AnyAll.cs

确定序列是否包含任何元素。

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static bool Any(System::Collections::Generic::IEnumerable<TSource> ^ source);

public static bool Any<TSource>(this System.Collections.Generic.IEnumerable<TSource> source);

static member Any : seq<'Source> -> bool

<Extension()>
Public Function Any(Of TSource) (source As IEnumerable(Of TSource)) As Boolean

类型参数

TSource

的元素 source的类型。

参数

source: IEnumerable<TSource>

检查 IEnumerable<T> 空虚。

Boolean

如果源序列包含任何元素，则 true;否则，false。

例外

ArgumentNullException

source 是 null。

示例

下面的代码示例演示如何使用 Any 来确定序列是否包含任何元素。

List<int> numbers = new List<int> { 1, 2 };
bool hasElements = numbers.Any();

Console.WriteLine("The list {0} empty.",
    hasElements ? "is not" : "is");

// This code produces the following output:
//
// The list is not empty.

' Create a list of Integers.
Dim numbers As New List(Of Integer)(New Integer() {1, 2})

' Determine if the list contains any items.
Dim hasElements As Boolean = numbers.Any()

' Display the output.
Dim text As String = IIf(hasElements, "not ", "")
Console.WriteLine($"The list is {text}empty.")

' This code produces the following output:
'
' The list is not empty.

方法返回的布尔值Any<TSource>(IEnumerable<TSource>)通常用于子句（Visual Basic 中的子句）where的谓词或对方法的Where直接调用Where<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)。下面的示例演示了此方法的 Any 这种用法。

class Pet
{
    public string Name { get; set; }
    public int Age { get; set; }
}
class Person
{
    public string LastName { get; set; }
    public Pet[] Pets { get; set; }
}

public static void AnyEx2()
{
    List<Person> people = new List<Person>
        { new Person { LastName = "Haas",
                       Pets = new Pet[] { new Pet { Name="Barley", Age=10 },
                                          new Pet { Name="Boots", Age=14 },
                                          new Pet { Name="Whiskers", Age=6 }}},
          new Person { LastName = "Fakhouri",
                       Pets = new Pet[] { new Pet { Name = "Snowball", Age = 1}}},
          new Person { LastName = "Antebi",
                       Pets = new Pet[] { }},
          new Person { LastName = "Philips",
                       Pets = new Pet[] { new Pet { Name = "Sweetie", Age = 2},
                                          new Pet { Name = "Rover", Age = 13}} }
        };

    // Determine which people have a non-empty Pet array.
    IEnumerable<string> names = from person in people
                                where person.Pets.Any()
                                select person.LastName;

    foreach (string name in names)
    {
        Console.WriteLine(name);
    }

    /* This code produces the following output:

       Haas
       Fakhouri
       Philips
    */
}

Structure Pet
    Public Name As String
    Public Age As Integer
End Structure

Structure Person
    Public LastName As String
    Public Pets() As Pet
End Structure

Sub AnyEx2()
    Dim people As New List(Of Person)(New Person() _
{New Person With {.LastName = "Haas",
                  .Pets = New Pet() {New Pet With {.Name = "Barley", .Age = 10},
                                     New Pet With {.Name = "Boots", .Age = 14},
                                     New Pet With {.Name = "Whiskers", .Age = 6}}},
  New Person With {.LastName = "Fakhouri",
                   .Pets = New Pet() {New Pet With {.Name = "Snowball", .Age = 1}}},
  New Person With {.LastName = "Antebi",
                   .Pets = New Pet() {}},
  New Person With {.LastName = "Philips",
                   .Pets = New Pet() {New Pet With {.Name = "Sweetie", .Age = 2},
                                      New Pet With {.Name = "Rover", .Age = 13}}}})

    ' Determine which people have a non-empty Pet array.
    Dim names = From person In people
                Where person.Pets.Any()
                Select person.LastName

    For Each name As String In names
        Console.WriteLine(name)
    Next

    ' This code produces the following output:
    '
    ' Haas
    ' Fakhouri
    ' Philips

End Sub

注解

注释

此方法不返回集合的任何一个元素。而是确定集合是否包含任何元素。

一旦可以确定结果，就会停止枚举 source 。

在Visual Basic查询表达式语法中，Aggregate Into Any() 子句转换为调用 Any。

另请参阅

适用于

Any<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)

Source:: AnyAll.cs

Source:: AnyAll.cs

Source:: AnyAll.cs

Source:: AnyAll.cs

Source:: AnyAll.cs

确定序列的任何元素是否满足条件。

public:
generic <typename TSource>
[System::Runtime::CompilerServices::Extension]
 static bool Any(System::Collections::Generic::IEnumerable<TSource> ^ source, Func<TSource, bool> ^ predicate);

public static bool Any<TSource>(this System.Collections.Generic.IEnumerable<TSource> source, Func<TSource,bool> predicate);

static member Any : seq<'Source> * Func<'Source, bool> -> bool

<Extension()>
Public Function Any(Of TSource) (source As IEnumerable(Of TSource), predicate As Func(Of TSource, Boolean)) As Boolean

类型参数

TSource

的元素 source的类型。

参数

source: IEnumerable<TSource>

IEnumerable<T>要对其应用谓词的元素。

predicate: Func<TSource,Boolean>

用于测试条件的每个元素的函数。

Boolean

true 如果源序列不为空，并且至少一个元素在指定的谓词中通过测试，否则，为 false.

例外

ArgumentNullException

source 或 predicate 为 null.

示例

下面的代码示例演示如何使用 Any 来确定序列中的任何元素是否满足条件。

class Pet
{
    public string Name { get; set; }
    public int Age { get; set; }
    public bool Vaccinated { get; set; }
}

public static void AnyEx3()
{
    // Create an array of Pets.
    Pet[] pets =
        { new Pet { Name="Barley", Age=8, Vaccinated=true },
          new Pet { Name="Boots", Age=4, Vaccinated=false },
          new Pet { Name="Whiskers", Age=1, Vaccinated=false } };

    // Determine whether any pets over age 1 are also unvaccinated.
    bool unvaccinated =
        pets.Any(p => p.Age > 1 && !p.Vaccinated);

    Console.WriteLine(
        "There {0} unvaccinated animals over age one.",
        unvaccinated ? "are" : "are not any");
}

// This code produces the following output:
//
//  There are unvaccinated animals over age one.

Structure Pet
    Public Name As String
    Public Age As Integer
    Public Vaccinated As Boolean
End Structure

Shared Sub AnyEx3()
    ' Create a list of Pets
    Dim pets As New List(Of Pet)(New Pet() _
                         {New Pet With {.Name = "Barley", .Age = 8, .Vaccinated = True},
                          New Pet With {.Name = "Boots", .Age = 4, .Vaccinated = False},
                          New Pet With {.Name = "Whiskers", .Age = 1, .Vaccinated = False}})

    ' Determine whether any pets over age 1 are also unvaccinated.
    Dim unvaccinated As Boolean =
pets.Any(Function(pet) pet.Age > 1 And pet.Vaccinated = False)

    ' Display the output.
    Dim text As String = IIf(unvaccinated, "are", "are not")
    Console.WriteLine($"There {text} unvaccinated animals over age 1.")
End Sub

' This code produces the following output:
'
' There are unvaccinated animals over age 1.

注解

注释

此方法不返回集合的任何一个元素。而是确定集合的任何元素是否满足条件。

一旦可以确定结果，就会停止枚举 source 。

在Visual Basic查询表达式语法中，Aggregate Into Any() 子句转换为调用 Any。

另请参阅

Aggregate 子句（Visual Basic）

适用于

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