**Course Title:** Ruby Programming: From Basics to Advanced Techniques **Section Title:** Introduction to Ruby and Setup **Topic:** Writing your first Ruby program: Hello, World! Now that we have set up our Ruby development environment and learned the basic syntax, it's time to write our first Ruby program. The traditional "Hello, World!" program is a great place to start, as it allows us to focus on the basics of writing and running a Ruby script. **Why "Hello, World!"?** The "Hello, World!" program has been a staple of introductory programming tutorials for decades. It may seem simple, but it actually teaches some fundamental concepts: 1. **Output**: How to print output to the console or screen. 2. **Syntax**: Basic syntax and structure of a programming language. 3. **Execution**: How to run a program. **Writing our first Ruby program** Open your text editor or IDE (Integrated Development Environment) and create a new file called `hello_world.rb`. The `.rb` extension indicates that this is a Ruby file. Add the following line of code to the file: ```ruby puts "Hello, World!" ``` Let's break down what's happening: * `puts` is a Ruby method that prints the string that follows it to the console. * `"Hello, World!"` is a string literal that contains the text we want to print. Save the file. **Running our first Ruby program** Open your terminal or command prompt and navigate to the directory where you saved `hello_world.rb`. You can do this using the `cd` command. For example: ```bash cd Desktop ``` Once you are in the correct directory, type the following command to run the program: ``` ruby hello_world.rb ``` This will execute the Ruby interpreter, which will read the code in `hello_world.rb` and run it. You should see the following output: ``` Hello, World! ``` Congratulations! You have just written and run your first Ruby program! **Key Concepts and Takeaways** * Every Ruby program needs a `.rb` extension. * `puts` is used to print output to the console. * Strings can be enclosed in double quotes or single quotes. * Use the `ruby` command to run a Ruby program. **Common Issues and Troubleshooting** * Make sure you are in the correct directory when running the program. * Ensure that the file name matches the one you specified in the `ruby` command. * Check for typos in your code. **Example Code and Use Cases** For a more complex example, you can modify the `hello_world.rb` file to ask the user for their name and then print out a personalized greeting: ```ruby print "What is your name? " name = gets.chomp puts "Hello, #{name}!" ``` This code uses the `print` method to prompt the user for their name, and then uses the `gets` method to read their input. The `chomp` method removes the newline character from the end of the input. Finally, it uses string interpolation to print out a custom greeting. **External Resources and Further Reading** * Official Ruby documentation: [https://ruby-doc.org/core-3.1.2/README_rdoc.html](https://ruby-doc.org/core-3.1.2/README_rdoc.html) * Ruby tutorial on Codecademy: [https://www.codecademy.com/learn/learn-ruby](https://www.codecademy.com/learn/learn-ruby) **Do you have any questions or need help with any of the concepts covered in this topic? Leave a comment below and we will respond as soon as possible.** Next topic: 'Conditional statements: if, else, unless, case' (Control Structures and Functions) Please refer to the course schedule for the next topic.