Agfdhyk

This is my ruby file with hash:

book.rb

class Book

  attr_accessor :title, :author, :language, :classification, :isbn, :book_id, :borrow_status







  def initialize(title, author, language, classification, isbn, book_id, borrow_status)

    @title = title

    @author = author

    @language = language

    @classification = classification

    @isbn = isbn

    @book_id = book_id

    @borrow_status = borrow_status

  end



  def bookid

    @book_id

  end



  def booklist

    @title = @title.split(/ |_|-/).map(&:capitalize).join(" ")

    @author = @author.split(/ |_|-/).map(&:capitalize).join(" ")

    @language = @language.capitalize

    @isbn.to_s

    @book_id.to_s



    {

        :Title => @title,

        :Author => @author,

        :Language => @language,

        :Classification => @classification,

        :ISBN => @isbn,

        :Book_ID => @book_id,

        :Status => @borrow_status,

    }

  end





end

for now, I already have five key-value pair for this hash, they are in ruby file named top.rb:

$books1 = Book.new("lonely planet: ireland","damian harper","english","tourism",9781786574459,1,"available")

$books2 = Book.new("ninteen eighty four","george orwell","english","literature",9781374677817, 2,"available")

$books3 = Book.new("japanese in 30 days","naomi ono","japanese","education",9787928365729,3,"available")

$books4 = Book.new("brand famous: how to get everyone talking about your business","linzi boyd","english","business",9780857084903,4,"borrowed")

$books5 = Book.new("SQL in 10 mins","ming zhong, xiaoxia liu","chinese","hi tech",9787115313980,5,"unavailable")

and using the method below to output the result:

    def status

      bookstatus = gets.chomp.to_s

      if bookstatus == "status"

       puts "Status:" + "n" + "#{$books1.booklist[:Book_ID]}: #{$books1.booklist[:Title]}: #{$books1.booklist[:Status]}"

       puts "#{$books2.booklist[:Book_ID]}:#{$books2.booklist[:Title]}: #{$books2.booklist[:Status]}"

       puts "#{$books3.booklist[:Book_ID]}:#{$books3.booklist[:Title]}: #{$books3.booklist[:Status]}"

       puts "#{$books4.booklist[:Book_ID]}:#{$books4.booklist[:Title]}: #{$books4.booklist[:Status]}"

       puts "#{$books5.booklist[:Book_ID]}:#{$books5.booklist[:Title]}: #{$books5.booklist[:Status]}"

   else

       puts "error"

end

end

For now, I am going to add some more value, I am going to let user enter the information of books (e.g., title = gets.chomp.to_s), and make a new key-value pair for the book added.

As I know, add new key-value pair to ruby is like below:

my_hash = {:a => 5}

my_hash[:key] = "value"

But, the hash in book.rb does not have any name, I tried to give it a name like

book_list = {

        :Title => @title,

        :Author => @author,

        :Language => @language,

        :Classification => @classification,

        :ISBN => @isbn,

        :Book_ID => @book_id,

        :Status => @borrow_status,

    }

it will output error.

My question is, I would like to know how can I add a new key-value pair to the hash in my ruby file, which has no name?

Thanks.

Changing the booklist method to this will solve your immediate problem:

  def booklist

    @booklist ||= {

        :Title => @title.split(/ |_|-/).map(&:capitalize).join(" "),

        :Author => @author.split(/ |_|-/).map(&:capitalize).join(" "),

        :Language => @language.capitalize,

        :Classification => @classification,

        :ISBN => @isbn.to_s,

        :Book_ID => @book_id.to_s,

        :Status => @borrow_status,

    }

  end

Now you can do booklist[:Xyz] = 'xyz'.

The code in your question has so many "Hello world!" -level mistakes, that it appears you still seem to have a bit to learn about Ruby basics, such as using variables, the difference between @isbn, isbn, $isbn, ISBN, or @@isbn, etc.

There are better "learn ruby" tutorials online than I'm ready to start here, so my answer is probably not very helpful.