Gain insights into Kotlin’s basics, including variable declarations, data types, conditions, loops, and functions. Discover how to write simple Kotlin scripts and transition to advanced programming.

Kotlin is quickly joining the ranks of the most popular programming languages. Now that Google supports Kotlin for Android app development as the primary choice over Java, we’ll only see more developers making the switch. So if you’re looking to get started with Android app development, then you’ve come to the right place.

This course will be your guide on getting started with Kotlin. We’ll go over all the language basics including variable declarations, data types and the type system to conditions, loops, and functions.

After this course, you’ll be able to write simple Kotlin scripts and applications. With this solid understanding of the language basics, you’ll be able to more easily follow more advanced material covering functional and object-oriented programming.

Homam B.

What a brilliant course, its not too long so its fairly easy to get through in a weekend. Goes through the fundimentals of Kotlin in just the right amount of detail. I would recommend this as a first step into Kotlin language

"Brilliant course"

Patricio M.

I have completed the course and I have to say that it's extremely well done

The examples used are clear and easy to follow

The code is very clean and the instructor strives to write clear and concise code and he explains concepts very clearly

Kudos for a job well done!

"Extremely well done"

Alan J.

Clear explanations, and well organized. Highly recommended.

"Highly recommended"

Raphael A.

Excellent course. It's a beginner course in programming, but even as a Java programmer I've been able to remember a lot of things and get productive quickly in Kotlin. The course is well structured and the teacher knows the subject (I bought another course from the teacher).

"Excellent course"

Kotlin Crash Course for Programmers

Functions separate useful chunks of code into a named entity you can reference in your code. Along with variables, they are the absolute fundamental language construct to avoid code duplication.

# Function Signatures

A *function signature* defines a function's name, inputs, and outputs. In Kotlin, it looks like this:

This signature defines a function named `fibonacci` with one input parameter named `index` of type `Int` and a return value of type `Long`. In other words, you give the function an integer and get back a `Long`. This function implements the well-known [Fibonacci sequence](https://en.wikipedia.org/wiki/Fibonacci_sequence).

# Declaring a Function

In a *function declaration*, both a function signature and a *function body* are required:

fun fibonacci(index: Int): Long {
  return if (index < 2) {
    1
  } else {
    fibonacci(index-2) + fibonacci(index-1)  // Calls `fibonacci` recursively
  }
}

The function body is a code block (thus surrounded by curly braces) and defines what the function does. The `return` keyword defines the return value of the function call.

> **Note:** Notice how the `return` keyword is moved outside of the condition blocks. This is possible because the `if` block is an expression and therefore has a value.

# Calling a Function

Once you have declared a function, you can call it by passing in a value for each required input parameter:

Learn how to modularize chunks of code into functions and how to call your functions in Kotlin. Understand the difference between function signatures and function declarations.

Hello Kotlin!

Variables and Data Types

Conditions

Collections

Loops

Functions

Equality Checks

Exception Handling

Summary

Basic Functions

Function Signatures #

Declaring a Function #