Case Statements

We also have another type of conditional in Ruby, the case statement conditional. Let's take a look:

atm_transaction = "withdraw"

case atm_transaction
when "withdraw"
  puts "Starts withdrawal process"
when "deposit"
  puts "Starts desposit process"
when "cancel"
  puts "Cancels transaction"
else
  puts "Sorry, we don't recognize this transaction"
end

Unlike the if/else conditional we learned above, with the case statement conditional, you specify a case condition with case (in this situation, a variable containing an ATM transaction) and then you "walk" down through the when options until you either find a match or run out of options. The case statement can also take an optional else condition that outputs if no matches are found. Let's look at one more:

score = 91

result = case score
  when 0..60
    "F"
  when 61..70
    "D"
  when 71..80
    "C"
  when 81..90
    "B"
  when 91..100
    "A"
  else "Invalid Score"
end

puts result

This time around we set a score, then set result equal to a case/when statement using score. When we call puts we can now see what the letter grade we received was based on that score. We're always awesome so of course we got the A here.

Exercise 5

Now let's try making a case statement. Make a variable called fav_command with your favorite terminal command stored inside as a string, then create a case/when statement for some common terminal commands you've learned so far (like ls or cd) and have it puts what that command does in your own words using your fav_command variable. Think of why a case statement might be more useful/easier than if/else in this kind of situation.