**Course Title:** Ruby Programming: From Basics to Advanced Techniques **Section Title:** Control Structures and Functions **Topic:** Conditional statements: if, else, unless, case **Introduction:** Conditional statements are a fundamental concept in programming that allow your code to make decisions based on certain conditions. In this topic, we will explore the if, else, unless, and case statements in Ruby, which are used to control the flow of your program and make decisions based on various conditions. **What are Conditional Statements?** Conditional statements are used to execute different blocks of code based on certain conditions. They allow your program to make decisions and take different actions depending on the outcome of a condition. **If Statement:** The if statement is used to execute a block of code if a certain condition is true. The syntax of the if statement in Ruby is as follows: ```ruby if condition # code to be executed if condition is true end ``` Example: ```ruby x = 5 if x > 10 puts "x is greater than 10" else puts "x is less than or equal to 10" end ``` In this example, the condition `x > 10` is false, so the code inside the else block is executed. **Else Statement:** The else statement is used to execute a block of code if the condition in the if statement is false. The syntax of the else statement in Ruby is as follows: ```ruby if condition # code to be executed if condition is true else # code to be executed if condition is false end ``` Example: ```ruby x = 5 if x > 10 puts "x is greater than 10" else puts "x is less than or equal to 10" end ``` In this example, the condition `x > 10` is false, so the code inside the else block is executed. **Unless Statement:** The unless statement is used to execute a block of code if a certain condition is false. The syntax of the unless statement in Ruby is as follows: ```ruby unless condition # code to be executed if condition is false end ``` Example: ```ruby x = 5 unless x > 10 puts "x is less than or equal to 10" end ``` In this example, the condition `x > 10` is true, so the code inside the if block is not executed. **Case Statement:** The case statement is used to execute different blocks of code based on the value of a variable. The syntax of the case statement in Ruby is as follows: ```ruby case variable when value1 # code to be executed if variable is equal to value1 when value2 # code to be executed if variable is equal to value2 else # code to be executed if variable is not equal to value1 or value2 end ``` Example: ```ruby x = 5 case x when 1..3 puts "x is between 1 and 3" when 4..6 puts "x is between 4 and 6" else puts "x is not between 1 and 6" end ``` In this example, the value of `x` is 5, so the code inside the second when block is executed. **Key Concepts:** * Conditional statements are used to control the flow of your program and make decisions based on certain conditions. * The if statement is used to execute a block of code if a certain condition is true. * The else statement is used to execute a block of code if the condition in the if statement is false. * The unless statement is used to execute a block of code if a certain condition is false. * The case statement is used to execute different blocks of code based on the value of a variable. **Practical Takeaways:** * Use the if statement to make decisions based on conditions. * Use the else statement to execute code if the condition in the if statement is false. * Use the unless statement to execute code if a condition is false. * Use the case statement to execute different blocks of code based on the value of a variable. **Exercise:** Write a Ruby program that uses the if, else, unless, and case statements to make decisions based on conditions. **Additional Resources:** * Ruby Documentation: Conditional Statements (https://ruby-doc.org/core-3.1.0/doc/syntax/control.html#label-Conditional+Statements) * W3Schools: Ruby Conditional Statements (https://www.w3schools.com/ruby/ruby_conditions.asp) **Leave a comment or ask for help if you have any questions or need further clarification on any of the concepts covered in this topic.**