Now we have completed the basics of using packages, let’s move on to comments.

Before Commenting…

“Don’t comment bad code — rewrite it.” — Brian W. Kernighan and P. J. Plaugher.

Try to make code as clean and self-explanatory before adding comments. They should be the icing on the cake rather than the filling!

Comments are useful for:

  • Explaining what the code does & why something was done a certain way
  • Outlining important or fragile blocks of code, which require extra care
  • Noting down what we need to do when we are writing the code
  • Disabling code without deleting it
  • Adding information to be picked up by the go doc tool (more on that later)


There are two types of comments in Go.

Line Comments

Line comments start with a // and the rest of the line is ignored by the compiler.

// This entire line is ignored by the compiler // fmt.Println("Does NOT print") fmt.Println("This gets printed!") // This part gets ignored

Note how you can add a // after the code, without affecting it.

Block Comments

Block comments can span multiple lines. They start with a /* and end with a */, enveloping everything inside:

/* This is ignored. This is also ignored. fmt.Println("This WON'T print!") */

In the example above we’ve commented out all three lines using a block comment.

Now let’s use some comments in our own code!



Use a line comment, //, to comment out Are we racing or coding?


Use a block comment, /* */ to comment out the first TWO fmt.Println() statements.


Run the program using the command line.

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