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List.Exists Method

Determines whether the List contains elements that match the conditions defined by the specified predicate.

Namespace: System.Collections.Generic
Assembly: mscorlib (in mscorlib.dll)

Public Function Exists ( _
	match As Predicate(Of T) _
) As Boolean
Dim instance As List(Of T)
Dim match As Predicate(Of T)
Dim returnValue As Boolean

returnValue = instance.Exists(match)
public boolean Exists (
	Predicate<T> match
public function Exists (
	match : Predicate<T>
) : boolean
Not applicable.



The Predicate delegate that defines the conditions of the elements to search for.

Return Value

true if the List contains one or more elements that match the conditions defined by the specified predicate; otherwise, false.

Exception typeCondition


match is a null reference (Nothing in Visual Basic).

The Predicate is a delegate to a method that returns true if the object passed to it matches the conditions defined in the delegate. The elements of the current List are individually passed to the Predicate delegate, and processing is stopped when a match is found.

This method performs a linear search; therefore, this method is an O(n) operation, where n is Count.

The following code example demonstrates the Exists method and several other methods that use the Predicate generic delegate.

A List of strings is created, containing 8 dinosaur names, two of which (at positions 1 and 5) end with "saurus". The code example also defines a search predicate method named EndsWithSaurus, which accepts a string parameter and returns a Boolean value indicating whether the input string ends in "saurus".

The Find, FindLast, and FindAll methods are used to search the list with the search predicate method, and then the RemoveAll method is used to remove all entries ending with "saurus".

Finally, the Exists method is called. It traverses the list from the beginning, passing each element in turn to the EndsWithSaurus method. The search stops and the method returns true if the EndsWithSaurus method returns true for any element. The Exists method returns false because all such elements have been removed.


In C# and Visual Basic, it is not necessary to create the Predicate<string> delegate (Predicate(Of String) in Visual Basic) explicitly. These languages infer the correct delegate from context and create it automatically.

Imports System
Imports System.Collections.Generic

Public Class Example

    Public Shared Sub Main()

        Dim dinosaurs As New List(Of String)


        For Each dinosaur As String In dinosaurs

        Console.WriteLine(vbLf & _
            "TrueForAll(AddressOf EndsWithSaurus: {0}", _
            dinosaurs.TrueForAll(AddressOf EndsWithSaurus))

        Console.WriteLine(vbLf & _
            "Find(AddressOf EndsWithSaurus): {0}", _
            dinosaurs.Find(AddressOf EndsWithSaurus))

        Console.WriteLine(vbLf & _
            "FindLast(AddressOf EndsWithSaurus): {0}", _
            dinosaurs.FindLast(AddressOf EndsWithSaurus))

        Console.WriteLine(vbLf & _
            "FindAll(AddressOf EndsWithSaurus):")
        Dim sublist As List(Of String) = _
            dinosaurs.FindAll(AddressOf EndsWithSaurus)

        For Each dinosaur As String In sublist

        Console.WriteLine(vbLf & _
            "{0} elements removed by RemoveAll(AddressOf EndsWithSaurus).", _
            dinosaurs.RemoveAll(AddressOf EndsWithSaurus))

        Console.WriteLine(vbLf & "List now contains:")
        For Each dinosaur As String In dinosaurs

        Console.WriteLine(vbLf & _
            "Exists(AddressOf EndsWithSaurus): {0}", _
            dinosaurs.Exists(AddressOf EndsWithSaurus))
    End Sub

    ' Search predicate returns true if a string ends in "saurus".
    Private Shared Function EndsWithSaurus(ByVal s As String) _
        As Boolean

        ' AndAlso prevents evaluation of the second Boolean
        ' expression if the string is so short that an error
        ' would occur.
        If (s.Length > 5) AndAlso _
            (s.Substring(s.Length - 6).ToLower() = "saurus") Then
            Return True
            Return False
        End If
    End Function
End Class

' This code example produces the following output:
'TrueForAll(AddressOf EndsWithSaurus: False
'Find(AddressOf EndsWithSaurus): Amargasaurus
'FindLast(AddressOf EndsWithSaurus): Dilophosaurus
'FindAll(AddressOf EndsWithSaurus):
'2 elements removed by RemoveAll(AddressOf EndsWithSaurus).
'List now contains:
'Exists(AddressOf EndsWithSaurus): False

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0

.NET Compact Framework

Supported in: 2.0

XNA Framework

Supported in: 1.0