Enumerable.Any<TSource> Method (IEnumerable<TSource>)
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Determines whether a sequence contains any elements.
Namespace: System.Linq
Assembly: System.Core (in System.Core.dll)
Syntax
'Declaration
<ExtensionAttribute> _
Public Shared Function Any(Of TSource) ( _
source As IEnumerable(Of TSource) _
) As Boolean
public static bool Any<TSource>(
this IEnumerable<TSource> source
)
Type Parameters
- TSource
The type of the elements of source.
Parameters
- source
Type: System.Collections.Generic.IEnumerable<TSource>
The IEnumerable<T> to check for emptiness.
Return Value
Type: System.Boolean
true if the source sequence contains any elements; otherwise, false.
Usage Note
In Visual Basic and C#, you can call this method as an instance method on any object of type IEnumerable<TSource>. When you use instance method syntax to call this method, omit the first parameter.
Exceptions
| Exception | Condition |
|---|---|
| ArgumentNullException | source is nulla null reference (Nothing in Visual Basic). |
Remarks
.gif "Note") Note: |
|---|
This method does not return any one element of a collection. Instead, it determines whether the collection contains any elements. |
The enumeration of source is stopped as soon as the result can be determined.
In Visual Basic query expression syntax, an Aggregate Into Any() clause translates to an invocation of Any.
Examples
The following code example demonstrates how to use Any to determine whether a sequence contains any elements.
' 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 ", "")
outputBlock.Text += "The list is " & text & "empty." & vbCrLf
' This code produces the following output:
'
' The list is not empty.
List<int> numbers = new List<int> { 1, 2 };
bool hasElements = numbers.Any();
outputBlock.Text += String.Format("The list {0} empty.",
hasElements ? "is not" : "is") + "\n";
// This code produces the following output:
//
// The list is not empty.
The Boolean value that the Any<TSource>(IEnumerable<TSource>) method returns is typically used in the predicate of a where clause (Where clause in Visual Basic) or a direct call to the Where<TSource>(IEnumerable<TSource>, Func<TSource, Boolean>) method. The following example demonstrates this use of the Any method.
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
outputBlock.Text &= name & vbCrLf
Next
' This code produces the following output:
'
' Haas
' Fakhouri
' Philips
End Sub
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)
{
outputBlock.Text += name + "\n";
}
/* This code produces the following output:
Haas
Fakhouri
Philips
*/
}
Version Information
Silverlight
Supported in: 5, 4, 3
Silverlight for Windows Phone
Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0
XNA Framework
Supported in: Xbox 360, Windows Phone OS 7.0
Platforms
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.