meet it

Name the error you expect, and only that one is caught.

A bare rescue catches almost everything, even your typos, which hides bugs. Name the exception instead. catches dividing by 0 and lets other errors crash as usual, so you still hear about them.

.to_i turns "abc" into 0 without a word. Integer("abc") is stricter: it raises an . You can stack several rescue lines, one for each kind of error, and Ruby runs the first one that matches.

["12", "abc", "0"].each do |answer|
  begin
    puts 60 / Integer(answer)
  rescue ArgumentError
    puts "#{answer} is not a number"
  rescue ZeroDivisionError
    puts "Cannot divide by zero"
  end
end

A missing file raises Errno::ENOENT, and you can rescue that by name too.

guess first

Which rescue runs? Guess the output.

Guess before you run it. Wrong guesses are how you learn, and nothing is marked.

begin
  puts Integer("12")
  puts Integer("twelve")
rescue ZeroDivisionError
  puts "Zero!"
rescue ArgumentError => error
  puts "Bad: #{error.message}"
end

your turn

Your turn. Check the ticket orders.

Fill in two answers, one in digits and one that is not a number. In the last blank, write the error that Integer raises.

Your code

press run to see what happens

fix it

A typo is hiding behind the rescue. Can you fix it?

Broken code to fix

press run to see what happens

"5" is a number, yet it says it is not. Something else is going wrong, and the bare rescue is hiding it.
Change rescue to rescue ArgumentError and run it. The real error, a NameError, will show itself.
The variable on line 3 is misspelt. Change answr to answer, then press run.

nailed it

you catch exactly the right error. :D

rescue ZeroDivisionError catches only that one kind of error.
Integer("abc") raises an ArgumentError instead of giving 0.
A bare rescue can hide your own typos.

new words in your collection

ZeroDivisionError
ArgumentError

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