What evaluates to false in Ruby?
ruby
Solution
`false` and `nil` are the only ones:
http://www.ruby-doc.org/core-2.1.1/FalseClass.html
Rails provides `present?` which also includes empty strings and empty arrays: http://api.rubyonrails.org/classes/Object.html#method-i-present-3F
Problem
`false` and `nil` evaluate to false in `Ruby`. Anything else? Please provide links to official/authoritative references. ``` 2.0.0p247 :001 > if true ; puts 'TRUE' ; else puts 'FALSE' ; end TRUE 2.0.0p247 :002 > if false ; puts 'TRUE' ; else puts 'FALSE' ; end FALSE 2.0.0p247 :003 > if nil ; puts 'TRUE' ; else puts 'FALSE' ; end FALSE 2.0.0p247 :004 > if 0 ; puts 'TRUE' ; else puts 'FALSE' ; end TRUE 2.0.0p247 :005 > if [] ; puts 'TRUE' ; else puts 'FALSE' ; end TRUE 2.0.0p247 :006 > if {} ; puts 'TRUE' ; else puts 'FALSE' ; end TRUE 2.0.0p247 :007 > if '' ; puts 'TRUE' ; else puts 'FALSE' ; end (irb):616: warning: string literal in condition TRUE ```