conditional_control_flow.rb

# Conditional Statement
# This program demonstrates the use of conditional statements in Ruby.
# Conditional statements allow you to execute different blocks of code based on certain conditions.
# You can use if statement, switch statement, switch expression, ternary operator, unless statement, and single line if statements to create conditional logic in your Ruby programs.

# If statement
# The if statement is used to execute a block of code if a specified condition is true. You can also use elsif and else to handle multiple conditions.
# If conditions
# - `if`: Executes the block of code if the condition is true.
# - `elsif`: Executes the block of code if the previous condition(s) were false and this condition is true.
# - `else`: Executes the block of code if all previous conditions were false.
# The syntax for an if statement is as follows:
# if condition
#   # code to execute if condition is true
# elsif another_condition
#   # code to execute if another_condition is true
# else
#   # code to execute if all conditions are false
# end
number = 10

if number > 0
  puts "The number is positive."
elsif number < 0
  puts "The number is negative."
else
  puts "The number is zero."
end

# Ternary operator
# The ternary operator is a shorthand way of writing an if-else statement. It takes three operands: a condition, a result for true, and a result for false.
# The syntax for the ternary operator is: `condition ? expression_if_true : expression_if_false`.
age = 18
message = age >= 18 ? "You are an adult." : "You are a minor."
puts message

# Unless statement
# The unless statement is the opposite of the if statement. It executes a block of code only if the specified condition is false.
# The syntax for an unless statement is as follows:
# unless condition
#   # code to execute if condition is false
# else
#   # code to execute if condition is true
# end
is_raining = false

unless is_raining
  puts "It's a nice day outside!"
else
  puts "Don't forget to take an umbrella!"
end

# Switch statement
# Ruby does not have a built-in switch statement like some other programming languages, but you can achieve similar functionality using a case statement. The case statement allows you to compare a value against multiple conditions and execute the corresponding block of code.
# The syntax for a case statement is as follows:
# case variable
# when value1
#   # code to execute if variable == value1
# when value2
#   # code to execute if variable == value2
# else
#   # code to execute if variable does not match any of the values
# end
day = "Monday"

case day
when "Monday"
  puts "It's the start of the week."
when "Friday"
  puts "It's almost the weekend!"
else
  puts "It's just another day."
end

# Switch expression
# In Ruby 2.7 and later, you can use the case statement as an expression, which means it can return a value. This allows you to assign the result of a case statement to a variable.
# The syntax for a case expression is similar to a case statement, but you can assign the result to a variable.
# variable = case variable
# when value1
#   expression_if_value1
# when value2
#   expression_if_value2
# else
#   expression_if_no_match
# end
day = "Tuesday"

message = case day
when "Monday"
  "It's the start of the week."
when "Friday"
  "It's almost the weekend!"
else
  "It's just another day."
end

puts message

# Or you can use then after when to write the case statement in a single line.
# variable = case variable
# when value1 then expression_if_value1
# when value2 then expression_if_value2
# else expression_if_no_match
# end
day = "Wednesday"

message = case day
when "Monday" then "It's the start of the week."
when "Friday" then "It's almost the weekend!"
else "It's just another day."
end

puts message

# Single line if statement
# You can also write an if statement in a single line using the modifier form. This is useful for simple conditions and can make your code more concise.
# The syntax for a single line if statement is: `puts "message" if condition`.
number = 5
puts "The number is positive." if number > 0
puts "The number is negative." if number < 0
puts "The number is zero." if number == 0