Errors

Ruby uses exceptions to report errors and other information when something in the program has gone wrong.

If an error has occurred, the Ruby program will end. For example:

puts 2 / 0

This will result in:

Traceback (most recent call last):
        1: from errors_in_ruby.rb:1:in `<main>'
errors_in_ruby.rb:1:in `/': divided by 0 (ZeroDivisionError)

Some common errors are:

• RuntimeError
• StandardError
• NoMethodError
• IOError
• TypeError
• ArgumentError

Rescuing Errors

Use the rescue keyword in a begin...end block to catch errors and report messages. The error can be as general as StandardError or as specific as ZeroDivisionError:

begin
  puts 2 / 0
rescue ZeroDivisionError
  puts "Can't divide by 0"
end