Boolean values (true, false, nil) in Ruby

Introduction

Boolean values help us decide if something is true or false. nil means nothing or no value.

Checking if a light is on or off in a smart home app.

Deciding if a user is logged in or not on a website.

Testing if a box is empty or has something inside.

Stopping a game when a player loses.

Checking if a variable has a value or is empty.

Syntax

Ruby

true
false
nil

true and false are Boolean values representing yes/no or on/off.

nil means no value or nothing, similar to null in other languages.

Examples

Assigning Boolean values and nil to variables.

Ruby

is_raining = true
is_sunny = false
no_value = nil

Using a Boolean value in a decision to print a message.

Ruby

if is_raining
  puts "Take an umbrella"
else
  puts "No umbrella needed"
end

Checking if a variable is nil (has no value).

Ruby

value = nil
if value.nil?
  puts "No value found"
end

Sample Program

This program decides what to do based on hunger and food availability using Boolean values and nil.

Ruby

is_hungry = true
has_food = false
meal = nil

if is_hungry && has_food
  meal = "Eating now"
elsif is_hungry && !has_food
  meal = "Need to buy food"
else
  meal = "Not hungry"
end

puts meal
puts "Meal variable is nil? #{meal.nil?}"

Important Notes

In Ruby, only false and nil are treated as false in conditions; everything else is true.

Use .nil? method to check if a variable is nil.

Summary

true and false represent yes/no or on/off.

nil means no value or nothing.

Use Boolean values to make decisions in your code.