using System;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        //dotnetfiddle.net/ReRWyr

        //Create the reference for the file

        TextFile jaredsFile = new TextFile();

        //Load the content of the file. jaredsFile will now have all the lines of the file.

        jaredsFile.ReadFile();

        string myLine;

        char productType;

        string sku;

    string year;

     string promo;

        myLine = jaredsFile.ReadLine();

        //PRODUCT TYPE

        productType = myLine[0];

        Console.WriteLine(productType);

        //SKU

        sku = myLine.Substring(1,5);

        Console.WriteLine(sku);

        //YEAR

        year = myLine.Substring(6,4);

        Console.WriteLine(year);

        //PROMO

            promo = myLine.Substring(10,2);

        Console.WriteLine(promo);

    }

}

​

public class TextFile

{

    private List<string> lines;

    private int nextLineIndex;

    ///Constructor for the file

    public TextFile()

    {

        lines = new List<string>();

        nextLineIndex = 0;

    }

    ///This method populates the file

    public void ReadFile()

    {

        //Each line has the following format TSSSSSYYYYPP

        string[] newValues = new string[]{

            "A75BEL2012FB",

            "CWSKEY2019NA",

            "BTWHDP2016GL",

            "APO7FN2019FB",

            "CSTCUP2017GL",

            "BPSTND2014NA",

            "AAMATO2020FB",

        };

        lines.AddRange(newValues);

        //Reset the index

        nextLineIndex = 0;

    }

    ///This method returns true if the file still has lines to return, or false if it already reached the EOF.

    public bool FileHasMoreLines()

    {

        return nextLineIndex < lines.Count;

    }

    public string ReadLine()

    {

        string textLine = "<<ERROR: FILE IS EMPTY>>";

        if (nextLineIndex < lines.Count)

        {

            textLine = lines[nextLineIndex];

            nextLineIndex++;

        }

        return textLine;

    }   

}