Ruby Interview Questions and answers

The General Ruby Interview Questions consists the most frequently asked questions in Ruby. This list of 100+ questions guage your familiarity with the Ruby. The q&a have been collected over a period of time from various blogs, forums and other sites

1. Ruby Interview Questions and FAQs

1.1 What is Ruby?

Ruby is a pure object-oriented programming language with a super clean syntax that makes programming elegant and fun. Ruby successfully combines Smalltalk's conceptual elegance, Python's ease of use and learning, and Perl's pragmatism. Ruby originated in Japan in the early 1990s, and has started to become popular worldwide in the past few years as more English language books and documentation have become available.

1.2 What is Rails?

Rails is an open source Ruby framework for developing database-backed web applications. What's special about that? There are dozens of frameworks out there and most of them have been around much longer than Rails. Why should you care about yet another framework? What would you think if I told you that you could develop a web application at least ten times faster with Rails than you could with a typical Java framework? You can--without making any sacrifices in the quality of your application! How is this possible? Part of the answer is in the Ruby programming language. Many things that are very simple to do in Ruby are not even possible in most other languages. Rails takes full advantage of this. The rest of the answer is in two of Rail's guiding principles: less software and convention over configuration. Less software means you write fewer lines of code to implement your application. Keeping your code small means faster development and fewer bugs, which makes your code easier to understand, maintain, and enhance. Very shortly, you will see how Rails cuts your code burden. Convention over configuration means an end to verbose XML configuration files--there aren't any in Rails! Instead of configuration files, a Rails application uses a few simple programming conventions that allow it to figure out everything through reflection and discovery. Your application code and your running database already contain everything that Rails needs to know!

1.3 How would you create a new ruby rail application?

To create a new ruby rail application rails my_app cd my_app

1.4 How do you comment out a block of code?

Use =begin and =end. =begin def my_commented_out_method end =end You could use successive # signs, but that's just tedious: # # def my commented_out_method # end #

1.5 What's the difference in scope for these two variables: @name and @@name?

@name is an instance variable and @@name is a class variable

1.6 What two delimiters are used for blocks?

Curly braces {...} and "do"..."end" Bonus: coding convention is to use curly braces if the code will fit on one line and "do"..."end" syntax if the block contains multiple lines.

1.7 How do you capitalize all characters in a string?

"this is my string".upcase If the string is in a variable: @my_string.upcase Note: The method: upcase! is another alternative. See next question regarding methods that end with an exclamation.

1.8 How do the following methods differ: @my_string.strip and @my_string.strip! ?

The strip! method modifies the variable directly. Calling strip (without the !) returns a copy of the variable with the modifications, the original variable is not altered.

1.9 What is the naming conventions for methods that return a boolean result?

Methods that return a boolean result are typically named with a ending question mark. For example: def active? return true #just always returning true end

1.10 What is the difference between nil and false in ruby?

False is a boolean datatype Nil is not a data type