Writing Comments

Comments Basics

Before we dive into more complex topics, let’s focus on a fundamental aspect of writing clean and maintainable code: writing comments.

Such lines are integral to any programming language. They allow developers to do the following:

leave notes explaining what exactly a certain part of the code does or how it works;
temporarily exclude certain parts of code from compilation to identify whether a certain part of the code causes errors;
write concise documentation for the code.

Types of Comments in Scala

Scala supports two main types of comments:

Single-Line Comments: As the name suggests, these comments span only a single line. They are marked by two forward slashes (//). Anything following // on the same line will be treated as a comment.

Main


              12345678
            
object Main {
  def main(args: Array[String]): Unit = {
	// Printing a greeting
    println("Hello!")
    println("1") // Printing a number
	// println("Goodbye")
  }	
}

Multi-Line Comments: These are used for longer comments that span multiple lines. They start with /* and end with */. Everything between these markers is considered a comment.

Main


              12345678
            
object Main {
  def main(args: Array[String]): Unit = {
    println("Hello!")
    /* An example of a multi-line comment 
	println("1")
	println("Goodbye") */
  }	
}

Best Practices for Writing Comments

While writing comments, keep the following best practices in mind:

Clarity: Ensure your comments are clear and easy to understand.
Relevance: Comment on parts of the code that are complex or not immediately obvious. Avoid stating the obvious.
Maintenance: Keep your comments updated as you update your code.
Brevity: Be concise. A comment should not be longer than necessary.

Task

The code below contains an error. Your task is to comment the line which causes this error.

Main


              123456
            
object Main {
  def main(args: Array[String]): Unit = {
    println("Hello")
	println('Goodbye')
  }
}

Everything was clear?

Thanks for your feedback!

Section 1. Chapter 5