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Operator

Kotlin provides a rich set of operators for performing operations on variables and values. These include arithmetic, comparison, logical, assignment, and more.

Arithmetic Operators​

Used for basic math operations:

  • + Addition
  • - Subtraction
  • * Multiplication
  • / Division
  • % Modulus (remainder)

Example::

val a = 10
val b = 3
println(a + b)  // 13
println(a - b)  // 7
println(a * b)  // 30
println(a / b)  // 3
println(a % b)  // 1

Comparison Operators​

Compare two values:

  • == Equal to
  • != Not equal to
  • < Less than
  • > Greater than
  • <= Less than or equal to
  • >= Greater than or equal to

Example:

val x = 5
val y = 10
println(x == y)  // false
println(x != y)  // true
println(x > y)   // false
println(x < y)   // true
println(x >= 5)  // true
println(x <= 3)  // false

Assignment Operators​

Assign values or perform operation and assign:

  • = Assign
  • += Add and assign
  • -= Subtract and assign
  • *= Multiply and assign
  • /= Divide and assign
  • %= Modulus and assign

Example:

var i = 3  // 1
i += 2     // 5
i -= 1     // 4
i *= 2     // 8
i /= 3     // 2
i %= 3     // 2

Logical Operators​

Used with boolean values:

  • && Logical AND
  • || Logical OR
  • ! Logical NOT

Example:

val p = true
val q = false
println(p && q)  // false
println(p || q)  // true
println(!p)      // false

Unary Operators​

Used to perform operations like negation and increment:

  • +a Unary plus
  • -a Unary minus
  • ++a Pre-increment
  • a++ Post-increment
  • --a Pre-decrement
  • a-- Post-decrement
  • !a Logical negation

Example:

var m = 7
println(+m)    // 7
println(-m)    // -7
println(++m)   // 8 (prefix increment)
println(m--)   // 8 (postfix decrement, then m becomes 7)
println(m)     // 7
val flag = false
println(!flag) // true

Type Check Operators​

  • is Checks if value is of a given type
  • !is Negated type check

Example::

val x: Any = "Hello"
println(x is String)  // true

Elvis Operator ?:​

Used to return a default value when expression is null:

val name: String? = null
val displayName = name ?: "Guest"
println(displayName)  // Guest

Bitwise Operators (Function form)​

Unlike Java, Kotlin uses named functions for bitwise ops:

  • shl() shift left
  • shr() shift right
  • ushr() unsigned shift right
  • and(), or(), xor(), inv()

Example::

val a = 5     // 0101
val b = 3     // 0011
println(a and b)  // 1
println(a or b)   // 7