Array.FindLastIndex Generic Method (T[], Int32, Generic Predicate)

public static int FindLastIndex<T> (
	T[] array,
	int startIndex,
	Predicate<T> 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.

startIndex

The zero-based starting index of the backward search.

match

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

Return Value

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

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.

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 overloads of the FindLastIndex generic method. An array 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 FindLastIndex(J[],Generic Predicate) method overload traverses the array backward from the end, passing each element in turn to the EndsWithSaurus method. The search stops when the EndsWithSaurus method returns true for the element at position 5.

Note
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.

The FindLastIndex(J[],Int32,Generic Predicate) method overload is used to search the array beginning at position 4 and continuing backward to the beginning of the array. It finds the element at position 1. Finally, the FindLastIndex(J[],Int32,Int32,Generic Predicate) method overload is used to search the range of three elements beginning at position 4 and working backward (that is, elements 4, 3, and 2). It returns –1 because there are no dinosaur names in that range that end with "saurus".

using System;

public class Example
{
    public static void Main()
    {
        string[] dinosaurs = { "Compsognathus", 
            "Amargasaurus",   "Oviraptor",      "Velociraptor", 
            "Deinonychus",    "Dilophosaurus",  "Gallimimus", 
            "Triceratops" };

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

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

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

        Console.WriteLine(
            "\nArray.FindLastIndex(dinosaurs, 4, 3, EndsWithSaurus): {0}",
            Array.FindLastIndex(dinosaurs, 4, 3, EndsWithSaurus));
    }

    // Search predicate returns true if a string ends in "saurus".
    private static bool EndsWithSaurus(String s)
    {
        if ((s.Length > 5) && 
            (s.Substring(s.Length - 6).ToLower() == "saurus"))
        {
            return true;
        }
        else
        {
            return false;
        }
    }
}

/* This code example produces the following output:

Compsognathus
Amargasaurus
Oviraptor
Velociraptor
Deinonychus
Dilophosaurus
Gallimimus
Triceratops

Array.FindLastIndex(dinosaurs, EndsWithSaurus): 5

Array.FindLastIndex(dinosaurs, 4, EndsWithSaurus): 1

Array.FindLastIndex(dinosaurs, 4, 3, EndsWithSaurus): -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.

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