**Course Title:** Ruby Programming: From Basics to Advanced Techniques **Section Title:** Control Structures and Functions **Topic:** Defining and calling functions/methods **Introduction** In Ruby, functions or methods are blocks of code that can be executed multiple times from different parts of your program. They are a fundamental concept in programming and are used extensively in Ruby. In this topic, we will cover the basics of defining and calling functions/methods in Ruby. **Defining Functions/Methods** A function or method in Ruby is defined using the `def` keyword followed by the method name and parameters in parentheses. Here is an example of a simple function that takes one parameter: ```ruby def greet(name) puts "Hello, #{name}!" end ``` In this example, `greet` is the method name and `name` is the parameter. The `puts` statement is the code that will be executed when the method is called. **Calling Functions/Methods** To call a function or method, you simply use the method name followed by parentheses containing any required parameters. Here is an example of calling the `greet` method: ```ruby greet("John") # Output: Hello, John! ``` **Key Concepts** * **Method signature**: The part of the method definition that specifies the method name and parameters. * **Method body**: The code that is executed when the method is called. * **Parameter**: A value passed to a method when it is called. **Examples** Here are a few more examples of functions/methods in Ruby: ```ruby # A function that takes two parameters and returns their sum def add(a, b) a + b end # A method that takes a string and returns its length def length(str) str.length end # A function that takes a list of numbers and returns their average def average(numbers) numbers.sum / numbers.length end ``` **Practical Takeaways** * Functions/methods are a powerful tool in Ruby that allow you to reuse code and make your programs more modular and maintainable. * When defining a function/method, make sure to include a clear and descriptive method name and parameter list. * When calling a function/method, make sure to include any required parameters in the correct order. **Exercise** Write a function that takes a string and returns its reverse. Use the `reverse` method to achieve this. ```ruby def reverse(str) # Your code here end ``` **Solution** ```ruby def reverse(str) str.reverse end ``` **Next Topic:** Understanding scope and block parameters. **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.**