Operator overloading concept in Kotlin - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is operator overloading in Kotlin?

Operator overloading allows you to provide custom implementations for standard operators (like +, -, *, etc.) for your own classes. This means you can define how operators behave when used with your objects.

beginner

How do you enable operator overloading for a function in Kotlin?

You mark the function with the keyword operator. For example, operator fun plus(other: MyClass): MyClass lets you use the + operator.

beginner

Which function name corresponds to the '+' operator in Kotlin operator overloading?

The function name is plus. Defining operator fun plus() lets you use the + operator with your class.

intermediate

Can you overload the assignment operator '=' in Kotlin?

No, Kotlin does not allow overloading the assignment operator '='. You can overload many operators, but '=' is not one of them.

intermediate

Example: How to overload the '*' operator for a class Vector to multiply by a scalar?

Define operator fun times(scalar: Double): Vector inside the Vector class. This lets you write val result = vector * 2.0.

Which keyword is used to enable operator overloading in Kotlin?

A overload

B fun

C operator

D override

The keyword operator is used before a function to enable operator overloading.

What function name should you use to overload the '+' operator?

A plus

B sum

C add

D append

The function name plus corresponds to the '+' operator in Kotlin.

Can you overload the '=' assignment operator in Kotlin?

A No, it is not allowed

B Only for data classes

C Yes, always

D Only with inline functions

Kotlin does not allow overloading the assignment operator '='.

Which of these operators can you overload in Kotlin?

A = (assignment)

B ?: (Elvis operator)

C && (logical AND)

D + (plus)

You can overload arithmetic operators like '+', but not logical operators like '&&' or assignment '='.

What is the correct way to overload the '*' operator for a class?

A operator fun multiply(other: ClassName): ClassName

B operator fun times(other: ClassName): ClassName

C fun times(other: ClassName): ClassName

D fun multiply(other: ClassName): ClassName

The '*' operator corresponds to the function named times and must be marked with operator.

Explain how operator overloading works in Kotlin and how you can define a custom '+' operator for your class.

Think about how you tell Kotlin what '+' means for your objects.

List some operators that can and cannot be overloaded in Kotlin and explain why assignment '=' cannot be overloaded.

Consider which operators affect basic language behavior.