As we build upon our programs, we’ll often need to update the values of variables following certain calculations. Assume a program that increases the current speed of a vehicle to match a speed limit of 55:

var currentSpeed = 45 
currentSpeed = currentSpeed + 10
print(currentSpeed) // Prints: 55

In order to increase and update the value of currentSpeed, we’ve added 10 to currentSpeed and reassigned it back to currentSpeed. Kotlin provides an even shorter syntax for operations like this with augmented assignment operators.

Augmented assignment operators execute a calculation and reassign its result to a variable all in one step. Each consists of an arithmetic operator immediately followed by the = operator. Take a look at the difference in syntaxes:

Long Syntax:

a = a + b

Short Syntax with an Augmented Assignment Operator:

a += b 

Here’s a breakdown of each:

Keeping the short syntax in mind, we can now refactor and optimize our previous program to its final, concise state:

currentSpeed += 10
println(currentSpeed) // Prints: 55 

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