Array.LastIndexOf(Of T) Method (T(), T)

Searches for the specified object and returns the index of the last occurrence within the entire Array.

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

'Declaration
Public Shared Function LastIndexOf(Of T) ( _
	array As T(), _
	value As T _
) As Integer

Type Parameters

T

The type of the elements of the array.

Parameters

array
Type: T()

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

value
Type: T

The object to locate in array.

Return Value

Type: System.Int32
The zero-based index of the last occurrence of value within the entire array, if found; otherwise, –1.

ExceptionCondition
ArgumentNullException

array is Nothing.

The Array is searched backward starting at the last element and ending at the first element.

The elements are compared to the specified value using the Object.Equals method. If the element type is a nonintrinsic (user-defined) type, the Equals implementation of that type is used.

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

The following code example demonstrates all three generic overloads of the LastIndexOf method. An array of strings is created, with one entry that appears twice, at index location 0 and index location 5. The LastIndexOf(Of T)(T(), T) method overload searches the entire array from the end, and finds the second occurrence of the string. The LastIndexOf(Of T)(T(), T, Int32) method overload is used to search the array backward beginning with index location 3 and continuing to the beginning of the array, and finds the first occurrence of the string. Finally, the LastIndexOf(Of T)(T(), T, Int32, Int32) method overload is used to search a range of four entries, beginning at index location 4 and extending backward (that is, it searches the items at locations 4, 3, 2, and 1); this search returns –1 because there are no instances of the search string in that range.

Imports System

Public Class Example

    Public Shared Sub Main()

        Dim dinosaurs() As String = { "Tyrannosaurus", _
            "Amargasaurus", _
            "Mamenchisaurus", _
            "Brachiosaurus", _
            "Deinonychus", _
            "Tyrannosaurus", _
            "Compsognathus" }

        Console.WriteLine()
        For Each dinosaur As String In dinosaurs
            Console.WriteLine(dinosaur)
        Next

        Console.WriteLine(vbLf & _
            "Array.LastIndexOf(dinosaurs, ""Tyrannosaurus""): {0}", _
            Array.LastIndexOf(dinosaurs, "Tyrannosaurus"))

        Console.WriteLine(vbLf & _
            "Array.LastIndexOf(dinosaurs, ""Tyrannosaurus"", 3): {0}", _
            Array.LastIndexOf(dinosaurs, "Tyrannosaurus", 3))

        Console.WriteLine(vbLf & _
            "Array.LastIndexOf(dinosaurs, ""Tyrannosaurus"", 4, 4): {0}", _
            Array.LastIndexOf(dinosaurs, "Tyrannosaurus", 4, 4))

    End Sub 
End Class 

' This code example produces the following output: 

'Tyrannosaurus 
'Amargasaurus 
'Mamenchisaurus 
'Brachiosaurus 
'Deinonychus 
'Tyrannosaurus 
'Compsognathus 

'Array.LastIndexOf(dinosaurs, "Tyrannosaurus"): 5 

'Array.LastIndexOf(dinosaurs, "Tyrannosaurus", 3): 0 

'Array.LastIndexOf(dinosaurs, "Tyrannosaurus", 4, 4): -1

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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