While every programmer is different, there is one experience we all share: getting an error message. An error, or bug, causes our programs to behave in unexpected ways.

When we receive an error message, it’s almost always because of something we wrote incorrectly in our code. As a result, the compiler cannot translate our program and returns an error message.

There are many different kinds of errors we can encounter. This may sound daunting, but luckily the Kotlin compiler provides accurate and descriptive error messages, allowing us to quickly and efficiently locate the issue.

For example, take a very close look at the following code:

fun main() { printlnn("To err is human.") }

When we run this, we receive the following error:

Error.kt:2:3: error: unresolved reference: printlnn
  printlnn("To err is human.")

This error message provides a lot of useful information:

  • Error.kt is the name of the file that contains the bug.
  • The first number (2) tells us the line in which the error exists.
  • The second number (3) tells us the character number in which the error lives on that line.
  • The text following error: describes what error we are encountering.

We received this error because we wrote printlnn instead of println and the compiler couldn’t recognize the instruction.

Once we fix and rerun our code, we get the following output:

To err is human.



Run the code in Error.kt.

We will receive an error message.


Read the error message and fix the code in the editor so that it can execute properly.

PS: Check the hint for additional help!

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