CODEWITHSUNDEEP
ruby
jonsanders101
jonsanders101

Reputation: 525

Why is return keyword required to exit loop?

In the test2 method below, why is the return keyword needed in order for the method's return to not equal nil?

In test, return isn't required. The last line the program evaluates (true or false) becomes the return

def test
  x = gets.chomp

  if x == 'yes'
    true
  else
    false
  end
end

result = test
puts result # PRINTS 'TRUE' OR 'FALSE'

But in test2, if return isn't given on the lines indicated, the return value of the method will be nil.

def test2
  while true
    reply = gets.chomp.downcase

    if (reply == 'yes' || reply == 'no')
      if reply == 'yes'
        true      # RETURN NEEDED HERE
       else
        false     # RETURN NEEDED HERE
       end
      break

     else
      puts 'Please answer "yes" or "no".'
    end
  end
end

result2 = test2
puts result2        # PRINTS NIL

The examples are adapted from Chris Pine's How to Program, where it states the return key is necessary here to quit the loop. But why should this return a value, if the last line to be evaluated is still either true or false?

Upvotes: 0

Views: 48

Answers (2)

Stefan
Stefan

Reputation: 114158

You can use break to provide a return value for while:

if reply == 'yes'
  break true
 else
  break false
end

Upvotes: 1

Mario F
Mario F

Reputation: 47279

if you don't use return, the last statement in your method is the while loop itself, which evaluates to nil. The result of the if inside your loop is not "carried" over when you break out of the loop

Upvotes: 3

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