Kotlin - Operators And Comments

Introduction

In this part, we are going to learn about operators and comments in Kotlin. Those who are willing to learn about Kotlin, Pros and Cons of it, and Kotlin Variables and DataTypes, please go through my articles on the links below.

Kotlin Operators

Operators are special characters which perform an operation on values or variables.

In Kotlin, there are several kinds of operators, as mentioned below.

Arithmetic Operator
Relation Operator
Assignment Operator
Unary Operator
Bitwise Operator
Logical Operator

Arithmetic Operator

Arithmetic operators are used to perform the basic mathematical operations, such as addition (+), subtraction (-), multiplication (*), division (/) etc.

Operator	Description	Expression
+	Addition	a+b
-	Subtraction	a-b
*	Multiplication	a*b
/	Division	a/b
%	Modulus	a%b

Example

fun main(args: Array<String>) {
val number1 = 12.5
val number2 = 3.5
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")
}

Output

number1 + number2 = 16.0

number1 - number2 = 9.0

number1 * number2 = 43.75

number1 / number2 = 3.57

number1 % number2 = 2.0

The +operator is also used for the concatenation of String values.

Example

Concatenation of Strings,

fun main(args: Array<String>) {
val start = "Abubackkar Shithik"
val middle = "Android Developer"
val end = "Trident Sqa"
val result = start + middle + end
println(result)
}

Output

Abubackkar Shithik Android Developer Trident Sqa

Relation Operator

Relation operator shows the relation and compares between values and variables.

Operator	Description	Expression
<	Less than	a<b
>	Greater than	a>b
<=	Less than or equal to	a<=b
>=	Greater than or equal to	a>=b
Equal ==	Is equal to	a==b
!=	Not equal to	a!=b

Example

fun main(args : Array<String>) {
val a = 5
val b = 10
val result = if (a > b) {
println("a is greater than b.")
a
} else{
println("b is greater than a.")
b
}
println("result= $result")
}

Output

b is greater than a

result =10

Assignment operator

Assignment operator "=" is used to assign a value to another variable. The assignment of value takes from right to left.

Operator	Description	Expression
+=	Add and assign	a+=b
-=	Sub and assign	a-=b
*=	Multiply and assign	a*=b
/=	Divide and assign	a/=b
%=	Mod and assign	a%=b

Example

fun main(args : Array<String>) {
var a =20;var b=5
a+=b
println("a+=b :"+ a)
a-=b
println("a-=b :"+ a)
a*=b
println("a*=b :"+ a)
a/=b
println("a/=b :"+ a)
a%=b
println("a%=b :"+ a)
}

Output

a+=b :25

a-=b :20

a*=b :100

a/=b :20

a%=b :0

Unary Operator

A unary operator is used with only a single operand.

Operator	Description	Expression
+	Unary Plus	+a
-	Unary Minus	-a
++	Increment by 1	++a
--	Decrement by 1	--a
!	not	!a

Example

fun main(args: Array<String>){
var a=10
var b=5
var flag = true
println("+a :"+ +a)
println("-b :"+ -b)
println("++a :"+ ++a)
println("--b :"+ --b)
println("!flag :"+ !flag)
}

Output

+a :10

-b :-5

++a :11

--b :4

!flag :false

Bitwise Operator

Unlike Java, there are no bitwise and bitshift operators in Kotlin. To perform these tasks, various functions (supporting infix notation) are there.

Named Function	Description	Expression
shl	Signed Shift Left	a.shl(b)
shr	Signed Shift Right	a.shr(b)
ushr	Unsigned Shift Right	a.ushr(b)
and	Bitwise and	a.and(b)
or	Bitwise or	a.or(b)
xor	Bitwise xor	a.xor(b)
inv	Bitwise inverse	a.inv()

Example

fun main(args: Array<String>){
var a=10
var b=2
println("a.shl(b): "+a.shl(b))
println("a.shr(b): "+a.shr(b))
println("a.ushr(b:) "+a.ushr(b))
println("a.and(b): "+a.and(b))
println("a.or(b): "+a.or(b))
println("a.xor(b): "+a.xor(b))
println("a.inv(): "+a.inv())
}

Output

a.shl(b): 40

a.shr(b): 2

a.ushr(b:) 2

a.and(b): 2

a.or(b): 10

a.xor(b): 8

a.inv(): -11

Logical Operators

There are three logical operators in Kotlin: Or, And, and Not denoted by ||, &&, ! respectively.

Operator	Description	Expression
\|\|	Return true if any expression are true	(a>b)\|\|(a>c)
&&	Return true if all expression are true	(a>b)&&(a>c)
!	Return Compliment of expression	a.not()

Example

fun main(args: Array<String>){
var a=10
var b=5
var c=15
var flag = false
var result: Boolean
result = (a>b) && (a>c)
println("(a>b) && (a>c) :"+ result)
result = (a>b) || (a>c)
println("(a>b) || (a>c) :"+ result)
result = !flag
println("!flag :"+ result)
}

Output

(a>b) && (a>c) :false

(a>b) || (a>c) :true

!flag :true

Kotlin – Comment

Comments are the statements that are used for documentation purposes. Comments are ignored by the compiler so that they don't get executed. We can also use it for providing information about the line of code. There are two types of comments in Kotlin.

Single line comment.
Multi-line comment.

Single line comment

Single line comment is used for commenting a single line of the statement. It is done by using '//' (double slash).

Multi-line comment

Multi-line comment is used for commenting multiple lines of a statement. It is done by using /* */ (start with slash strict and end with star slash).

Conclusion

In this article, we learned about operators and comments in Kotlin. In the next part, we will learn about Control Expressions, Return, and Jump.

Next in this series: Kotlin Control Expressions and Loops