**Course Title:** Ruby Programming: From Basics to Advanced Techniques **Section Title:** Control Structures and Functions **Topic:** Write Ruby scripts that use control structures and methods to solve problems. **Objective:** In this lab, you will learn how to write Ruby scripts that utilize control structures and methods to solve real-world problems. Control structures and methods are essential components of programming, allowing you to manage the flow of your programs and reuse code. By the end of this lab, you will be able to write efficient and effective Ruby scripts that apply control structures and methods to solve problems. **Lab Requirements:** 1. Review the concepts of control structures (conditional statements and loops) and methods in Ruby. 2. Practice writing Ruby scripts that use control structures and methods to solve problems. **Lab Exercises:** **Exercise 1: Using Conditional Statements to Calculate the Grading System** Create a Ruby script that calculates the grade based on the student's score. Use the following grading system: - 0-40: F - 41-60: D - 61-80: C - 81-90: B - 91 and above: A ```ruby # Define a method to calculate the grade def calculate_grade(score) if score >= 91 "A" elsif score >= 81 "B" elsif score >= 61 "C" elsif score >= 41 "D" else "F" end end # Test the method puts calculate_grade(85) # Output: B puts calculate_grade(92) # Output: A puts calculate_grade(30) # Output: F ``` **Exercise 2: Using Loops to Calculate the Sum of Numbers** Create a Ruby script that calculates the sum of the first 'n' natural numbers. Use a loop to iterate from 1 to 'n' and calculate the sum. ```ruby # Define a method to calculate the sum of the first 'n' natural numbers def calculate_sum(n) sum = 0 (1..n).each do |i| sum += i end sum end # Test the method puts calculate_sum(5) # Output: 15 (1+2+3+4+5) puts calculate_sum(10) # Output: 55 (1+2+3+4+5+6+7+8+9+10) ``` **Exercise 3: Using Methods to Simulate a Bank Account** Create a Ruby script that defines a method to simulate a bank account. The method should have the following attributes: - `balance`: initializes the account balance to 0 - `deposit(amount)`: adds the deposit amount to the balance - `withdraw(amount)`: deducts the withdrawal amount from the balance - `check_balance`: returns the current balance ```ruby # Define a class to represent the BankAccount class BankAccount def initialize @balance = 0 end def deposit(amount) @balance += amount end def withdraw(amount) @balance -= amount if @balance >= amount end def check_balance @balance end end # Create a new bank account account = BankAccount.new account.deposit(500) account.withdraw(100) puts account.check_balance # Output: 400 ``` **Tips and Best Practices:** - Use meaningful variable names and method names to improve code readability. - Keep methods short and focused on a single task. - Use comments to explain the purpose of each method. - Use conditionals and loops to control the program flow. **Additional Resources:** - [Ruby Documentation: Control Expressions](https://ruby-doc.org/docs/ruby-doc-bundle/UsersGuide/rg/control.html) - [Ruby Documentation: Method](https://ruby-doc.org/docs/ruby-doc-bundle/UsersGuide/rg/definingmethods.html) **Conclusion:** In this lab, you wrote Ruby scripts that applied control structures and methods to solve real-world problems. You calculated the grading system, calculated the sum of numbers, and simulated a bank account. Remember to practice and experiment with different control structures and methods to reinforce your understanding. For questions or help, please leave a comment below. **Next Topic:** Introduction to classes and objects (Object-Oriented Programming in Ruby).