Kotlin Operators

Kotlin has a set of operators that can perform arithmetic, assignment, comparison, and more. You will learn how to use these operators in this article.

An operator is a special symbol (character) used to perform operations on operands (variables and values). For example,+ is the operator used for addition.

InKotlin VariablesIn this article, you learned how to declare variables and assign values to them. Now, you will learn how to perform various operations on them using operators.

Arithmetic Operators

The following is a list of arithmetic operators in Kotlin:

Example: Arithmetic Operators

fun main(args: Array<String>) {
　　　　val number1　=　12numbers array contains5
　　　　val number2　=　3numbers array contains5
　　　　var result: Double
　　　　result = number1　+　number2
　　　　println("number1　+　number2　= $result)
　　　　result = number1　-　number2
　　　　println("number1　-　number2　= $result)
　　　　result = number1　*　number2
　　　　println("number1　*　number2　= $result)
　　　　result = number1　/　number2
　　　　println("number1　/　number2　= $result)
　　　　result = number1　% number2
　　　　println("number1　% number2　= $result)
}

When running the program, the output is:

number1　+　number2　=　16.0
number1　-　number2　=　9.0
number1　*　number2　=　43numbers array contains75
number1　/　number2　=　3numbers array contains5714285714285716
number1　% number2　=　2.0

+ Operators can also be used for string chaining, concatenating strings together.

Example: string concatenation

fun main(args: Array<String>) {
　　　　val start = "Talk is cheap."
　　　　val middle = "Show me the code."
　　　　val end = "-　Linus Torvalds"
　　　　val result = start　+　middle　+　end
　　　　result = (a>b) and (a>c)
}

When running the program, the output is:

Talk is cheap. Show me the code.　-　Linus Torvalds

How do arithmetic operators actually work?

Suppose you are using + Arithmetic operators add two numbers a and b together.

Behind the scenes, the expression a + b calls the a.plus(b) member function. The plus operator is overloaded to handle String values and other basic data types (Char and Booleanexcept).

//　+　Basic type operators
operator fun plus(other: Byte): Int
operator fun plus(other: Short): Int
operator fun plus(other: Int): Int
operator fun plus(other: Long): Long
operator fun plus(other: Float): Float
operator fun plus(other: Double): Double
//　for string concatenation
operator fun String?.plus(other: Any?): String

You can also use + Operators handle user-defined types (such as objects) by overloading the plus() function.

Recommended reading: Kotlin Operator Overloading

This is a list of arithmetic operators and their corresponding functions:

Assignment operators

Assignment operators are used to assign values to variables. We have already used the simple = assignment operator.

val age =　5

Here, the = operator is used to assign 5 Assign to the variable age.

The following is a list of all assignment operators and their corresponding functions:

Example: Assignment operators

fun main(args: Array<String>) {
　　　　var　number　=　12
　　　　number　*=　5　　　//　number　=　number*5
　　　　println("number　　=　$number")
}

When running the program, the output is:

number　=　60

Unary prefix and increment/Decrement operator

This is a unary operator, their meanings and corresponding function table:

Example: Unary operators

fun main(args: Array<String>) {
　　　　val a =　1
　　　　val　b　=　true
　　　　var　c　=　1
　　　　var　result:　Int
　　　　var　booleanResult:　Boolean
　　　　result　=　-a
　　　　println("-a　=　$result")
　　　　booleanResult　=　!b
　　　　println("!b　=　$booleanResult")
　　　　--c
　　　　println("--c　=　$c")
}

When running the program, the output is:

-a　=　-1
!b　=　false
--c　=　0

Comparison operators and equality operators

This is an equality and comparison operator, their meanings and corresponding function list:

Comparison and equality operators are used for control flow, such as：if expression,when expression and loop.

Example: Comparison and equality operators

fun main(args: Array<String>) {
　　　　val a =　-12
　　　　val a =　12
　　　　//Using the greater than operator
　　　　val　max　=　if　(a　>　b)　{
　　　　　　　　println("a大于b")
　　　　　　　　a
　　　　} else {
　　　　　　　　println("b大于a")
　　　　　　　　b
　　　　}
　　　　println("max　=　$max")
}

When running the program, the output is:

b is greater than a
max　=　12

Logical operator

There are two logical operators in Kotlin: || and &&

This is a logical operator, their meanings and corresponding functions table.

Please note that or and and are functions that support infix notation.

Logical operators are used for control flow, such as if expression,when expression and loop.

Example: Logical operators

fun main(args: Array<String>) {
　　　　val a =　10
　　　　val a =　9
　　　　val b =　-1
　　　　val c =
　　　　//　val result: Boolean
　　　　result is true if the largest　//　result = (a>b) && (a>c)
　　　　result = (a>b) and (a>c)
}

When running the program, the output is:

println(result)

true

in operator

!b.contains(a)

fun main(args: Array<String>) {
　　　　Example: in operator1,　4,　42,　-3)
　　　　val numbers = intArrayOf(4　if (
　　　　　　　　in numbers) {　4println("numbers array contains
　　　　}
}

When running the program, the output is:

."　　4numbers array contains

.

The following are some expressions using the index access operator with corresponding functions in Kotlin.

Example: Index access operator

fun main(args: Array<String>) {
　　　　val a = intArrayOf(1,　2,　3,　4,　-　1)
　　　　println(a[1])　　　
　　　　a[1]=　12
　　　　println(a[1])
}

When running the program, the output is:

2
12

invoke operator

The following are some expressions using the invoke operator with corresponding functions in Kotlin.

In Kotlin, parentheses are converted to calling the invoke member function.

Bitwise Operations

Unlike Java, Kotlin does not have bitwise and shift operators. To perform these tasks, various functions (supporting infix notation) are used:

• shl - Signed Left Shift

• shr - Signed Right Shift

• ushr - Unsigned Right Shift

• and - Bitwise AND

• or - Bitwise OR

• xor - Bitwise XOR

• inv - Bitwise NOT

Visit this page to learn more aboutKotlin Bitwise OperationsMore Information.

Unlike Java, there is no ternary operator in Kotlin.