Enumerable.Any(Of TSource) Method (IEnumerable(Of TSource))
Determines whether a sequence contains any elements.
Namespace: System.Linq
Assembly: System.Core (in System.Core.dll)
'Declaration <ExtensionAttribute> _ Public Shared Function Any(Of TSource) ( _ source As IEnumerable(Of TSource) _ ) As Boolean
Type Parameters
- TSource
The type of the elements of source.
Parameters
- source
- Type: System.Collections.Generic.IEnumerable(Of TSource)
The IEnumerable(Of T) to check for emptiness.
Return Value
Type: System.Booleantrue 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(Of TSource). When you use instance method syntax to call this method, omit the first parameter.| Exception | Condition |
|---|---|
| ArgumentNullException | source is Nothing. |
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.
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.
The Boolean value that the Any(Of TSource)(IEnumerable(Of 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(Of TSource)(IEnumerable(Of TSource), Func(Of 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
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