Introduction to Ruby Conditionals

Our daily life contains a set of conditionals whose job is to define us as individuals, these conditionals are introduced to us from the very first day:

Basic
```
if
```
expression

if user.status == "online"
  puts "hello world"
end

Ruby syntax provides the necessary elements to translate any conditional programming sequence into manageable and easy to read lines of code.

IF / ELSIF / ELSE STATEMENT

The

if

expression acts as a question and the outcome is determined by the answer to that question, with the help of the

elsif

and

else

statements, the possibilities are endless:

if user.mood == "happy"
  puts "time to study"
elsif user.mood == "sad"
  puts "time to play"
else 
  puts "time to code"
end

The if
statement evaluates anything we put in front of him, if the result returns

true

the condition is accepted and the piece of code inside gets executed, if the result returns

false

nil

(null) then we continue with the next condition, in this case

elsif

(else if) and the same process applies, if the result of

elsif

true

then it should output the message

"time to play"

, and finally if no condition is

true

, the

else

statement is executed.

IF AS A MODIFIER

As with the example above, the difference here is that first we need to write the "answer" or the code to be executed, then we pass the if
statement followed by the "question" or condition, which it's executed if the result is

true

puts "it's true!" if 1 > 0
# returns "it's true"

alarm.sound = off if current_day = 'saturday' || current_day = 'sunday'

UNLESS STATEMENT

Unlike the if
statement who checks for a true
value, the

unless

statement does the opposite and checks for false
or nil
:

unless cellphone.battery.percentage > 14
  cellphone.start_charge
end

We can combine the unless
expression only with the

else

statement:

unless job.isDone?
  puts "go back to work"
else
  puts "good job!"
end

job.isDone = true
# returns "good job!"

UNLESS AS A MODIFIER

Just as his relative if
, unless
can be used as a modifier serving the same purpose but only executing itself when the result is false
or nil:

Examples:

puts "it's not right!" unless 4 > 3
# 4 > 3 is true so code doesn't execute

alarm.sound = on unless current_time < "7:00am"

CASE / WHEN / ELSE STATEMENT

The case
statement is another Ruby conditional that can be used as an alternative to if / unless
, it's most frequently used to structure and create efficient code when there is a wide number of possible outcomes:

case fuel_level
when 71...100
  puts "Fuel Level: High"
when 41...70
  puts "Fuel Level: Medium"
when 21...40
  puts "Fuel Level: Low"
else
  puts "Fuel Level: Very Low"
end

fuel_level: 12
# returns "Fuel Level: Very Low"

case
is the expression to be evaluated, the

when

expression contains each one of the conditions, if a condition returns true
, the code inside is executed and concludes with the end
statement, finally the else
expression acts as the default condition to be executed if none of the case conditions return true
.

Links

Ruby Official Website https://www.ruby-lang.org/en/

Ruby Documentation https://www.ruby-lang.org/en/documentation/

Ruby Control Expressions https://docs.ruby-lang.org/en/2.7.0/syntax/control_expressions_rdoc.html

If you made it this far i hope this article helped you in one way or another, thanks for reading!