nil.to_i returning 0 instead of raising an exception doesn't make a lot of sense logically. Understanding Absence in Ruby: Present, Blank, Nil, Empty.

The #<=> is used by various methods to compare objects, for example Enumerable#sort, Enumerable#max etc.

The object is repeated every time for each enum. Just for educational purpose.

In the previous section, we’ve covered the “nil” construct in Ruby. Anything can potentially be nil, and every object can answer to the “nil?” method. Can I return nothing in ruby? This can and has caused hours of confusion and head-banging-against-wall for beginners, who can’t figure out why everything is suddenly nil. How can you get 0 from nil? to return true when none of the collection members are false or nil. – JosephK Jul 1 '16 at 16:48 You can create an empty hash with the new class method − months = Hash.new You can also use new to create a hash with a default value, which is otherwise just nil − months = Hash.new( "month" ) or months = Hash.new "month" When you … Passes each element of the collection to the given block. For example: myarray = [1,2,3] myarray << some_method def some_method if Date.today.day > 15 return "Trololo" else return __NOTHING__ end end So if today is 11'th March myarray won't add new item. Implicit return.

nil is "falsey", and if used directly in a conditional - or combined using logical operators &&, || etc, will behave the same as false, and your uses of it should work as you intend.. 0 means self is equal to other. It can represent nothing and, since every expression in Ruby has a return value, nil is also a useful proxy for certain behavior.
; Use break to quit from a block and from the method that yielded to the block.break accepts a value that supplies the result of the expression it is “breaking” out of. However, it is usually better practice to return true or false values from methods that behave like booleans. If you attempt to access a hash with a key that does not exist, the method will return nil. Every method always returns exactly one object. There is ONLY one nil object, with an object_id of 4 (or 8 in 64-bit Ruby), this is part of why nil is special. The method call restaurant_a2(10) would return nil instead of "Ribeye" Why?

For many beginning Rubyists, especially those having experience in other programming languages such as Java or C, checking whether variable is nil may seem a little bit confusing. IOW, we need "scripting language" functionality. The method will return true for a given object if it’s nil, false, empty or a whitespace string. Maybe throw something into the console at dev-level, just to help troubleshoot if/when you get nil unexpectedly. 変数cにはメソッド hoge2の返り値=> nilが代入されています。 ここまでで分かるのは、メソッドはreturnなりで、返す値を指定されていない場合、返り値がないので、 => nil を返り値として返します。 つまり、putsがnilを返すのも同じ理由です。 余談ですが、 In case no object is given, it return nil for each enum. You don’t have to return the last line of a method. In Ruby, a method always return exactly one single thing (an object). Here’s where nil comes in, we use it because it’s the closest thing we can get to a generic Null Object.