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Array.FindLast Generic Method

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

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

public static T FindLast<T> (
	T[] array,
	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.
Not applicable.

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 last 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 backward in the Array, starting with the last element and ending with the first 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 demonstrates the Find, FindLast, and FindAll generic methods. 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 Find generic method traverses the array from the beginning, passing each element in turn to the EndsWithSaurus method. The search stops when the EndsWithSaurus method returns true for the element "Amargasaurus".

NoteNote:

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 FindLast generic method is used to search the array backward from the end. It finds the element "Dilophosaurus" at position 5. The FindAll generic method is used to return an array containing all the elements that end in "saurus". The elements are displayed.

The code example also demonstrates the Exists and TrueForAll generic methods.

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.Exists(dinosaurs, EndsWithSaurus): {0}", 
            Array.Exists(dinosaurs, EndsWithSaurus));

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

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

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

        Console.WriteLine(
            "\nArray.FindAll(dinosaurs, EndsWithSaurus):");
        string[] subArray = 
            Array.FindAll(dinosaurs, EndsWithSaurus);

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

    // 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.Exists(dinosaurs, EndsWithSaurus): True

Array.TrueForAll(dinosaurs, EndsWithSaurus): False

Array.Find(dinosaurs, EndsWithSaurus): Amargasaurus

Array.FindLast(dinosaurs, EndsWithSaurus): Dilophosaurus

Array.FindAll(dinosaurs, EndsWithSaurus):
Amargasaurus
Dilophosaurus
 */

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
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