Ruby Building Blocks


Welcome to Ruby Building Blocks! Since you’ve already done a decent chunk of Ruby in the Web Development 101 Course (if not, go do that first!), this should start as a healthy refresher of what you’ve already learned with Variables, Data Types, Strings, and Methods.

But this lesson will take you much deeper and further than you went before, so don’t think you’ve got a free pass. There’s a whole lot of stuff to cover. These first couple of lessons cover the broadest swathe of material of the entire Ruby course, so get stretched out and warmed up, it’s time to dive in!

Learning Outcomes

Look through these now and then use them to test yourself after doing the assignment:

Numbers, Operators and Expressions:

  • What’s the difference between an Integer and a Float?
  • Why should you be careful when converting back and forth between integers and floats?
  • What’s the difference between =, ==, and ===?
  • How do you do exponents in Ruby?
  • What is a range?
  • How do you create a range?
  • What’s the difference between (1..3) and (1...3)?
  • What are three ways to create a range?


  • What’s the difference between single and double quotes?
  • What is string interpolation?
  • What are escape characters?
  • What are line breaks?
  • How do you make other things into strings?
  • How do you concatenate strings?
  • How do you access a specific character or substring?
  • How do you split up strings into arrays?
  • How are strings and arrays similar?
  • How do you get and clean up user input on the command line?
  • What does it mean that strings are “mutable” and why care?
  • What is a symbol?
  • How is a symbol different from a string?
  • What is a Regular Expression (RegEx)?
  • How can you center or right-justify a string?


  • What are three ways to create an array?
  • How do you prepopulate the array with default data?
  • How do you access items in an array?
  • How can you access a specific group of items in an array?
  • How do you modify the items in an array?
  • How do you combine arrays?
  • How do you find the values in one array that aren’t in another?
  • How do you find values in both arrays?
  • What is the difference between push/pop and shift/unshift?
  • What is the shovel operator?
  • How is > arr.pop different from > arr[-1]?
  • How is pushing or <<ing another array into your array different from just adding them together?
  • How do you delete items in an array?
  • Why should you be careful deleting items in an array?
  • How can you convert arrays to strings?
  • How can you convert from other data types to arrays?
  • How can you figure out if an array contains a particular value?
  • How do you find the biggest item in an array?
  • How do you find the smallest item in an array?
  • How do you remove any duplicates from your array?
  • How do you find out how big an array is?
  • How do you put an array in order?
  • What are the naming conventions for arrays?
  • What should you store in arrays?


  • What is a hash?
  • What are keys and values?
  • How is a hash similar to an Array?
  • How is a hash different from an Array?
  • What are 3 ways to create a hash?
  • What is the hash rocket?
  • How do you access data in a hash?
  • How do you change data in a hash?
  • What types of data are good to store in a hash?
  • What are options hashes?
  • How do you delete data from a hash?
  • How do you add hashes together?
  • How do you list out all the keys or values?
  • How do you see if the hash contains a key or value?
  • What is a set?

Dates and Times:

  • How do you get the current date and time?
  • How do you find just the Year? Month? Hour? Second? Weekday?
  • How do you create a Time specifically for 12/25/2013?
  • How do you find how many days have passed between two Time’s?
  • What’s the difference between UTC and GMT and Local times?
  • How would you find out the time that was 100 seconds ago? 10 days ago?

Other Random Stuff:

  • What is nil?
  • How do you check if something is nil?
  • What’s the difference between nil and blank and empty?
  • Are the following nil or empty? * " ", "", [], [""], {}
  • What’s the difference between puts and p and print?
  • What does inspect do?
  • What do +=, -=, *= and /= do?
  • What is parallel assignment?
  • What’s the easiest way to swap two variables?


  1. You should have already completed Learn to Program in the Web Development 101 course to start with.
  2. Do the full Codecademy Introduction to Ruby section from their Ruby Track.
  3. Take a look at the Ruby Date and Time explanation from TutorialsPoint. No need to memorize all the Time Formatting Directives, just know what they are and where to find them.
  4. Do this great little Regex Tutorial and the example problems (should only take an hour or so)
  5. Glance over this list of Escape Characters in Ruby and keep it for future reference. You’ll probably only end up using \n newlines and \t tabs.
  6. For a deeper look at certain underserved pieces of the above material, check out these posts from Erik Trautman:
    1. Ruby Explained: Numbers, Operators and Expressions
    2. Ruby Explained: Objects and Methods
    3. Ruby Explained: Strings
    4. Ruby Explained: Arrays
    5. Ruby Explained: Hashes
    6. Ruby Explained: Dates and Times
    7. Ruby Explained: Other Random Tidbits

Test Yourself

Note: If you want to actually write and run your own Ruby code, you can either use IRB from the command line (type irb after the prompt), or run it from a script file using $ ruby ./your_file_name_in_the_current_directory.rb, or use the online editor at

  1. Make sure you can do the Beginner Ruby Quiz #1 from Code Quizzes.
  2. Make sure you go back up and look at all the questions from the “Learning Outcomes” section. See if you can do most of them without looking back through the text.

Additional Resources

This section contains helpful links to other content. It isn’t required, so consider it supplemental for if you need to dive deeper into something.

Ruby Programming

Ruby Building Blocks

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