// C# Extension Method

// Doc: https://csharp-extension.com/en/method/1002638/array-findlastindex

​

// @nuget: Z.ExtensionMethods

​

using System;

using System.Drawing;

public class Program

{

    public static void Main()

    {

        string[] dinosaurs = { "Compsognathus",

        "Amargasaurus",   "Oviraptor",      "Velociraptor",

        "Deinonychus",    "Dilophosaurus",  "Gallimimus",

        "Triceratops" };

​

        Console.WriteLine();

        foreach (string dinosaur in dinosaurs)

        {

            Console.WriteLine(dinosaur);

        }

​

        // C# Extension Method: Array - FindLastIndex

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

        Console.WriteLine("\nArray.FindIndex(dinosaurs, 2, EndsWithSaurus): {0}", dinosaurs.FindLastIndex(2, EndsWithSaurus));

        Console.WriteLine("\nArray.FindIndex(dinosaurs, 2, 3, EndsWithSaurus): {0}", dinosaurs.FindLastIndex(2, 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;

        }

    }

}