<ExtensionAttribute> _
Public Shared Function Where(Of TSource) ( _
    source As IEnumerable(Of TSource), _
    predicate As Func(Of TSource, Boolean) _
) As IEnumerable(Of TSource)

Dim source As IEnumerable(Of TSource)
Dim predicate As Func(Of TSource, Boolean)
Dim returnValue As IEnumerable(Of TSource)

returnValue = source.Where(predicate)

public static IEnumerable<TSource> Where<TSource>(
    this IEnumerable<TSource> source,
    Func<TSource, bool> predicate
)

[ExtensionAttribute]
public:
generic<typename TSource>
static IEnumerable<TSource>^ Where(
    IEnumerable<TSource>^ source, 
    Func<TSource, bool>^ predicate
)

JScript does not support generic types or methods.

Usage Note

This method is implemented by using deferred execution. The immediate return value is an object that stores all the information that is required to perform the action. The query represented by this method is not executed until the object is enumerated either by calling its GetEnumerator method directly or by using foreach in Visual C# or For Each in Visual Basic.

In query expression syntax, a where (Visual C#) or Where (Visual Basic) clause translates to an invocation of Where<(Of <(TSource>)>)(IEnumerable<(Of <(TSource>)>), Func<(Of <(TSource, Boolean>)>)).

The following code example demonstrates how to use Where<(Of <(TSource>)>)(IEnumerable<(Of <(TSource>)>), Func<(Of <(TSource, Boolean>)>)) to filter a sequence.

' Create a list of strings.
Dim fruits As New List(Of String)(New String() _
                        {"apple", "passionfruit", "banana", "mango", _
                         "orange", "blueberry", "grape", "strawberry"})

' Restrict the results to those strings whose 
' length is less than six.
Dim query As IEnumerable(Of String) = _
    fruits.Where(Function(fruit) fruit.Length < 6)

' Display the results.
Dim output As New System.Text.StringBuilder
For Each fruit As String In query
    output.AppendLine(fruit)
Next
MsgBox(output.ToString())

' This code produces the following output:
'
' apple
' mango
' grape

List<string> fruits =
    new List<string> { "apple", "passionfruit", "banana", "mango", 
                    "orange", "blueberry", "grape", "strawberry" };

IEnumerable<string> query = fruits.Where(fruit => fruit.Length < 6);

foreach (string fruit in query)
{
    Console.WriteLine(fruit);
}
/*
 This code produces the following output:

 apple
 mango
 grape
*/

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

.NET Framework

.NET Compact Framework

XNA Framework

Reference

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