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Array.Find Generic Method

Note: This method is new in the .NET Framework version 2.0.

Searches for an element that matches the conditions defined by the specified predicate, and returns the first occurrence within the entire Array.

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

'Declaration
Public Shared Function Find(Of T) ( _
	array As T(), _
	match As Predicate(Of T) _
) As T
'Usage
Dim array As T()
Dim match As Predicate(Of T)
Dim returnValue As T

returnValue = Array.Find(array, match)
J# supports the use of generic types and methods, but not the declaration of new ones.
JScript does not support generic types and methods.

Type Parameters

T

The type of the elements of the array.

Parameters

array

The one-dimensional, zero-based Array to search.

match

The Predicate that defines the conditions of the element to search for.

Return Value

The first element that matches the conditions defined by the specified predicate, if found; otherwise, the default value for type T.

Exception typeCondition

ArgumentNullException

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

-or-

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 array are individually passed to the Predicate, moving forward in the Array, starting with the first element and ending with the last element. Processing is stopped when a match is found.

This method is an O(n) operation, where n is the Length of array.

The following code example uses a Predicate delegate with the Find generic method to search an array of Point structures. The method the delegate represents, ProductGT10, returns true if the product of the X and Y fields is greater than 100,000. The Find method calls the delegate for each element of the array, returning the first point that meets the test condition.

NoteNote

Visual Basic and C# users do not need to create the delegate explicitly, or to specify the type argument of the generic method. The compilers determine the necessary types from the method arguments you supply.

Imports System
Imports System.Drawing

Public Class Example

    Public Shared Sub Main()

        ' Create an array of five Point structures.
        Dim points() As Point = { new Point(100, 200), _
            new Point(150, 250), new Point(250, 375), _
            new Point(275, 395), new Point(295, 450) }

        ' To find the first Point structure for which X times Y 
        ' is greater than 100000, pass the array and a delegate 
        ' that represents the ProductGT10 method to the Shared
        ' Find method of the Array class.
        Dim first As Point = Array.Find(points, _
            AddressOf ProductGT10)

        ' Note that you do not need to create the delegate 
        ' explicitly, or to specify the type parameter of the 
        ' generic method, because the compiler has enough
        ' context to determine that information for you.

        ' Display the first structure found.
        Console.WriteLine("Found: X = {0}, Y = {1}", _
            first.X, first.Y)
    End Sub

    ' This method implements the test condition for the Find
    ' method.
    Private Shared Function ProductGT10(ByVal p As Point) As Boolean
        If p.X * p.Y > 100000 Then
            Return True
        Else
            Return False
        End If
    End Function
End Class

' This code example produces the following output:
'
'Found: X = 275, Y = 395

Windows 98, Windows 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 .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0

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