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In this guide we will discuss about operators in Kotlin. An operator is a symbol that tells the compiler to perform specific mathematical or logical manipulations. Kotlin is rich in built-in operators and provide the following types of operators:

• Arithmetic Operators
• Relational Operators
• Assignment Operators
• Unary Operators
• Logical Operators
• Bitwise Operations

Now let’s look into these Kotlin Operators one by one.

(a) Arithmetic Operators

Kotlin arithmetic operators are used to perform basic mathematical operations such as addition, subtraction, multiplication and division etc.

Example

Following example shows different calculations using Kotlin Arithmetic Operators:

fun main(args: Array<String>) {
   val x: Int = 40
   val y: Int = 20

   println("x + y = " +  (x + y))
   println("x - y = " +  (x - y))
   println("x / y = " +  (x / y))
   println("x * y = " +  (x * y))
   println("x % y = " +  (x % y))
}

When you run the above Kotlin program, it will generate the following output:

x + y = 60
x - y = 20
x / y = 2
x * y = 800
x % y = 0

(b) Relational Operators

Kotlin relational (comparison) operators are used to compare two values, and returns a Boolean value: either true or false.

Example

Following example shows different calculations using Kotlin Relational Operators:

fun main(args: Array<String>) {
   val x: Int = 40
   val y: Int = 20

   println("x > y = " +  (x > y))
   println("x < y = " +  (x < y))
   println("x >= y = " +  (x >= y))
   println("x <= y = " +  (x <= y))
   println("x == y = " +  (x == y))
   println("x != y = " +  (x != y))
}

When you run the above Kotlin program, it will generate the following output:

x > y = true
x < y = false
x >= y = true
x <= y = false
x == y = false
x != y = true

(c) Assignment Operators

Kotlin assignment operators are used to assign values to variables.

Following is an example where we used assignment operator = to assign a values into two variables:

fun main(args: Array<String>) {
   val x: Int = 40
   val y: Int = 20
   
   println("x = " +  x)
   println("y = " +  y)
}

When you run the above Kotlin program, it will generate the following output:

x = 40
y = 20

Following is one more example where we used assignment operator += to add the value of self variable and assign it back into the same variable:

fun main(args: Array<String>) {
   var x: Int = 40

   x += 10
      
   println("x = " +  x)
}

When you run the above Kotlin program, it will generate the following output:

x = 50

Following is a list of all assignment operators:

Example

Following example shows different calculations using Kotlin Assignment Operators:

fun main(args: Array<String>) {
   var x: Int = 40

   x += 5
   println("x += 5 = " + x )
   
   x = 40;
   x -= 5
   println("x -= 5 = " +  x)
   
   x = 40
   x *= 5
   println("x *= 5 = " +  x)
   
   x = 40
   x /= 5
   println("x /= 5 = " +  x)
   
   x = 43
   x %= 5
   println("x %= 5 = " + x)
}

When you run the above Kotlin program, it will generate the following output:

x += 5 = 45
x -= 5 = 35
x *= 5 = 200
x /= 5 = 8
x %= 5 = 3

(d) Unary Operators

The unary operators require only one operand; they perform various operations such as incrementing/decrementing a value by one, negating an expression, or inverting the value of a boolean.

Following is the list of Kotlin Unary Operators:

Example

Following example shows different calculations using Kotlin Unary Operators:

fun main(args: Array<String>) {
   var x: Int = 40
   var b:Boolean = true

   println("+x = " +  (+x))
   println("-x = " +  (-x))
   println("++x = " +  (++x))
   println("--x = " +  (--x))
   println("!b = " +  (!b))
}

When you run the above Kotlin program, it will generate the following output:

+x = 40
-x = -40
++x = 41
--x = 40
!b = false

Here increment (++) and decrement (–) operators can be used as prefix as ++x or –x as well as suffix as x++ or x–. The only difference between the two forms is that in case we use them as prefix then operator will apply before expression is executed, but if use them as suffix then operator will apply after the expression is executed.

(e) Logical Operators

Kotlin logical operators are used to determine the logic between two variables or values:

Following is the list of Kotlin Logical Operators:

Example

Following example shows different calculations using Kotlin Logical Operators:

fun main(args: Array<String>) {
   var x: Boolean = true
   var y:Boolean = false

   println("x && y = " +  (x && y))
   println("x || y = " +  (x || y))
   println("!y = " +  (!y))
}

When you run the above Kotlin program, it will generate the following output:

x && y = false
x || y = true
!y = true

(e) Kotlin Bitwise Operations

It does not have any bitwise operators but Kotlin provides a list of helper functions to perform bitwise operations.

Following is the list of Kotlin Bitwise Functions:

Example

Following example shows different calculations using Kotlin bitwise functions:

fun main(args: Array<String>) {
   var x:Int = 60	  // 60 = 0011 1100  
   var y:Int = 13	  // 13 = 0000 1101
   var z:Int

   z = x.shl(2)       // 240 = 1111 0000
   println("x.shl(2) = " +  z)
   
   z = x.shr(2)       // 15 = 0000 1111
   println("x.shr(2) = " +  z)
   
   z = x.and(y)       // 12 = 0000 1100
   println("x.and(y)  = " +  z)
   
   z = x.or(y)        // 61 = 0011 1101
   println("x.or(y)  = " +  z)
   
   z = x.xor(y)       // 49 = 0011 0001
   println("x.xor(y)  = " +  z)
   
   z = x.inv()        // -61 = 1100 0011
   println("x.inv()  = " +  z)
}

When you run the above Kotlin program, it will generate the following output:

x.shl(2) = 240
x.shr(2) = 15
x.and(y)  = 12
x.or(y)  = 61
x.xor(y)  = 49
x.inv()  = -61

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