Infix functions for readable calls in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is an infix function in Kotlin?

An infix function is a special kind of function that allows you to call it using infix notation, which means you can write it between its receiver and argument without dots or parentheses, making the code more readable.

beginner

How do you declare an infix function in Kotlin?

You declare an infix function by adding the keyword infix before the function name. It must be a member function or an extension function with a single parameter and no varargs or default values.

intermediate

Example: What does this Kotlin code do?<br>

infix fun Int.times(str: String) = str.repeat(this)

This code defines an infix function times for Int that repeats the given string the number of times equal to the integer. For example, 2 times "Hi" returns "HiHi".

intermediate

What are the requirements for a function to be used as infix in Kotlin?

It must be a member or extension function, have a single parameter, not accept varargs or default parameter values, and be marked with the infix keyword.

beginner

Why use infix functions? Give a real-life analogy.

Infix functions make code look like natural language, improving readability. Like saying "I give you" instead of "I.give(you)", it feels more like a simple conversation.

Which keyword is used to declare an infix function in Kotlin?

A infix

B inline

C override

D fun

The keyword infix is used before the function name to declare an infix function.

What is a requirement for the parameter of an infix function?

A It must be nullable

B It can have multiple parameters

C It must be a vararg parameter

D It must be a single parameter without default values

Infix functions must have exactly one parameter without default values or varargs.

How would you call an infix function named connect on an object a with argument b?

A connect(a, b)

B a.connect(b)

C a connect b

D connect a b

Infix functions allow calling like a connect b without dots or parentheses.

Can an infix function be a top-level function (not inside a class or object)?

A Only if marked inline

B No, it must be a member or extension function

C Yes, always

D Only if it has no parameters

Infix functions must be member or extension functions, not top-level standalone functions.

What is the benefit of using infix functions?

A Improves code readability by allowing natural language style calls

B Makes functions run faster

C Allows multiple parameters

D Automatically handles null safety

Infix functions improve readability by letting you write calls that look like natural language.

Explain what an infix function is and how to declare one in Kotlin.

Think about how you write functions that look like natural language.

Describe a simple example of an infix function and how it improves code readability.

Use a real-life analogy or simple string repetition example.