using System;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Arrays - a collection data type ");

        Console.WriteLine("Types of Collections: List<DataType>, Array[], Dictionary<Key,Value>");

        //---------------------arrays----------------------------------

        //Datatype[]Identifer; <------Basic syntax to declare an empty array of datatypes 

        string[] cars = {"Ford", "Chevy","BMW", "Dodge", "Tesla"}; //you will need to place each item in your collection sepereated by commas

        int[] grade = {95, 36, 89, 94, 100};

        double num1 = 1.0, num2 = 45.6, num3 = 3.145;

        double[] myDoubles = {num1,num2,num3};

        //how do we access the numbers insdie of array? Arrays are an orderd collection of items; meaning they have an index nuber associated with each item

        //The index numbers start with 0 and go up to the last item in the collection (Nth item)

        //To access an indvidual item in the array we want one of the index numbers to receive that item

        Console.WriteLine("My car is: "+cars[2]); //notice that the index is alwyas  3 less than the count**remember this**

        Console.WriteLine("My first item inside myDoubles is: "+myDoubles[0]);

        //we can also alter a item via its index number

        Console.WriteLine("Before changing index 0:" +cars[0]);

        cars[0] = "Mercedes";

        Console.WriteLine("after changing index 0:" +cars[0]);

        Console.WriteLine("------------------------------------------");

        //iterataes through an array

        for(int i = 0;i < cars.Length;i++)

        {

            Console.WriteLine(cars[i]+" = "+i+ ", ");

        }

        Console.WriteLine("");

        int changeWhat = 0;

        do

        {

        Console.WriteLine("Please choose the index that you want to change");

        changeWhat = Convert.ToInt32(Console.ReadLine());

            if(changeWhat >= 0)

            {

                if(changeWhat < cars.Length) 

                {

                    break;

                }

            } 

        }

        while (true);

        Console.WriteLine("Please enter the car you want to replace " +cars[changeWhat]+" with: ");

        cars[changeWhat] = Console.ReadLine(); //Change the value of the index the user has choosen 

        Console.WriteLine("

    }

}