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Array.LastIndexOf Generic Method (T[], T, Int32)

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

Searches for the specified object and returns the index of the last occurrence within the range of elements in the Array that extends from the first element to the specified index.

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

public static int LastIndexOf<T> (
	T[] array,
	T value,
	int startIndex
)
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.

value

The object to locate in array.

startIndex

The zero-based starting index of the backward search.

Return Value

The zero-based index of the last occurrence of value within the range of elements in array that extends from the first element to startIndex, if found; otherwise, –1.

Exception typeCondition

ArgumentNullException

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

ArgumentOutOfRangeException

startIndex is outside the range of valid indexes for array.

The Array is searched backward starting at startIndex 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 number of elements from the beginning of array to startIndex.

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(J[],J) method overload searches the entire array from the end, and finds the second occurrence of the string. The LastIndexOf(J[],J,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(J[],J,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.

using System;

public class Example
{
    public static void Main()
    {
        string[] dinosaurs = { "Tyrannosaurus",
            "Amargasaurus",
            "Mamenchisaurus",
            "Brachiosaurus",
            "Deinonychus",
            "Tyrannosaurus",
            "Compsognathus" };

        Console.WriteLine();
        foreach(string dinosaur in dinosaurs)
        {
            Console.WriteLine(dinosaur);
        }

        Console.WriteLine(
            "\nArray.LastIndexOf(dinosaurs, \"Tyrannosaurus\"): {0}", 
            Array.LastIndexOf(dinosaurs, "Tyrannosaurus"));

        Console.WriteLine(
            "\nArray.LastIndexOf(dinosaurs, \"Tyrannosaurus\", 3): {0}", 
            Array.LastIndexOf(dinosaurs, "Tyrannosaurus", 3));

        Console.WriteLine(
            "\nArray.LastIndexOf(dinosaurs, \"Tyrannosaurus\", 4, 4): {0}", 
            Array.LastIndexOf(dinosaurs, "Tyrannosaurus", 4, 4));
    }
}

/* 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
 */

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

.NET Compact Framework

Supported in: 2.0
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