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jamiefdhurst/isbns.rb

Created July 26, 2012 12:57
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This is me learning "Ruby"...
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isbns.rb
#!/usr/bin/env ruby
def is_valid_isbn13?(isbn13)
sum = 0
13.times { |i| sum += i % 2 == 0 ? isbn13[i].to_i : isbn13[i].to_i * 3 }
0 == sum % 10
end
puts "Loading file and reading ISBNs..."
isbns = []
File.open("isbns.txt", "r").each_line do |line|
isbns.push(line)
end
puts "Cleaning ISBNs..."
isbns.collect! do |isbn|
isbn = isbn.scan(/\d/).join('')
end
puts "Checking ISBNs..."
isbns.each do |isbn|
sum = 0
if (isbn.length != 13 or is_valid_isbn13?(isbn) == false)
puts " - #{isbn} is invalid..."
isbns.delete(isbn)
else
puts " - #{isbn} is valid..."
end
end
@richquick
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richquick commented Jul 27, 2012

This does the same thing and is hopefully a bit more Ruby-ish.

Hope it's useful..

#!/usr/bin/env ruby

class String

  def remove_non_digits
    self.scan(/\d/).join('')
  end

  def remove_non_digits!
    replace remove_non_digits
  end

  def is_valid_isbn13?

    isbn13 = self.remove_non_digits!

    sum = 0
    13.times { |i| sum += i % 2 == 0 ? isbn13[i].to_i : isbn13[i].to_i * 3 }
    0 == sum % 10

  end

end

File.open("isbns.txt", "r").each do |potential_isbn|

  if potential_isbn.is_valid_isbn13?
    message = " is a valid ISBN13"
  else
    message = " is not a valid ISBN 13"
  end

  puts potential_isbn + message

end

@jackfranklin
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jackfranklin commented Jul 27, 2012

@richquick In:

  def remove_non_digits
    isbn = self.scan(/\d/).join('')
  end

No need to do isbn = as you're just returning it.

@richquick
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richquick commented Jul 27, 2012

fair point. Updated.

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