Enumerable.Any 方法
定义
重要
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确定序列中是否包含元素或存在元素满足指定条件。
重载
| Any<TSource>(IEnumerable<TSource>) |
确定序列是否包含任何元素。 |
| Any<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>) |
确定序列中是否存在任意一个元素满足条件。 |
Any<TSource>(IEnumerable<TSource>)
- 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
source 的元素类型。
参数
- source
- IEnumerable<TSource>
要检查是否为空的 IEnumerable<T>。
返回
如果源序列包含任何元素，则为 true；否则为 false。
例外
source 为 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 Visual Basic) 中子句 (Where 子句的谓词where或对 方法的Where<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)直接调用。 以下示例演示了 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
注意
此方法不返回集合中的任何一个元素， 相反，它确定集合是否包含任何元素。
一旦可以确定结果，就会停止 的 source 枚举。
在 Visual Basic 查询表达式语法中， Aggregate Into Any() 子句转换为 的调用 Any。
另请参阅
适用于
Any<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)
- Source:
- AnyAll.cs
- Source:
- AnyAll.cs
- Source:
- AnyAll.cs
确定序列中是否存在任意一个元素满足条件。
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
source 的元素类型。
参数
- source
- IEnumerable<TSource>
一个 IEnumerable<T>，其元素将应用谓词。
返回
如果源序列不为空，并且至少有一个元素通过指定谓词中的测试，则为 true；否则为 false。
例外
source 或 predicate 为 null。
示例
下面的代码示例演示如何使用Any以确定序列中是否有任意一个元素满足条件。
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 == false);
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
注意
此方法不返回集合中的任何一个元素， 而是确定集合中是否存在任何元素满足条件。
一旦可以确定结果，就会停止 的 source 枚举。
在 Visual Basic 查询表达式语法中， Aggregate Into Any() 子句转换为 的调用 Any。
