Augmented Assignment

Part of the Fundamentals section of Coddy's Kotlin journey. Lesson 21 of 93.

When you need to update a variable's value based on its current value, Kotlin provides augmented assignment operators. These combine an arithmetic operation with assignment into a single, shorter expression.

Instead of writing x = x + 5, you can write x += 5. Both do the same thing, but the augmented version is cleaner and more common in real code:

fun main() {
    var score = 10
    score += 5   // Same as: score = score + 5
    println(score)  // Prints: 15
}

Each arithmetic operator has an augmented assignment version:

Operator	Example	Equivalent To
`+=`	`x += 3`	`x = x + 3`
`-=`	`x -= 3`	`x = x - 3`
`*=`	`x *= 3`	`x = x * 3`
`/=`	`x /= 3`	`x = x / 3`
`%=`	`x %= 3`	`x = x % 3`

fun main() {
    var balance = 100
    balance -= 25   // Subtract 25
    balance *= 2    // Double it
    println(balance)  // Prints: 150
}

Remember, these operators modify the variable, so you must use var, not val.

Challenge

Easy

Write a function applyOperations that takes start, addValue, and multiplyValue and returns the final result after applying augmented assignment operations.

Starting with the initial value, first add addValue to it, then multiply the result by multiplyValue.

Logic:

Start with the start value
Use += to add addValue
Use *= to multiply by multiplyValue

Parameters:

start (Int): The initial value
addValue (Int): The value to add
multiplyValue (Int): The value to multiply by

Returns: The final result after both operations (Int)

Try it yourself

fun applyOperations(start: Int, addValue: Int, multiplyValue: Int): Int {
    // Write code here
}

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Fundamentals

1Introduction

The Language Hello World!Comments Recap - Launch Message

4Operators Part 1

Arithmetic Operators Modulo OperatorAugmented AssignmentComparison Operators Recap - Simple Math

7Basic IO

Println Function String Templates ReadLine Input Type Conversion Recap - Years Until Retirement Recap - True or False

10Functions

Declare A Function Parameters And Arguments Return Values Named Arguments Default Values Single Expression Functions Recap - Sigma Function Recap - Validation Function

13Iterating Over Sequences

Iterating Over Elements WithIndex Method Iterating Over Strings P1 Iterating Over Strings P2 Recap - Indexed Letters

16Final Challenges

Flat Asterisk Pyramid Pattern Finder What To Buy

Practice on your own: Kotlin playground