Ranges in Kotlin (rangeTo() function example)

In this article, we will learn about the ranges in Kotlin: This contains example on rangeTo() function, rangeTo() is used to range expressions.
Submitted by Aman Gautam, on November 26, 2017

Kotlin Range Expressions

In Kotlin, Range expressions are defined in rangeTo() function whose operator form looks like '..'. Defining range is very simple in Kotlin.

Examples of Kotlin Range Expressions

Here are few examples for ranges,

Example: Print Numbers in a Range

This loop will iterate number from 1 to 5 in ascending order.

for(i in 1..5)
print(i)

Output

Note: This code is similar to i= 1 to i<= 5

Example: Print Numbers in Reverse Order in a Range

If we want to iterate in reverse order, we can use downTo() function as in example below.

for(i in 5 downTo 1){
	print(i)
}

Output

Example: Print Numbers in a Range with Steps

Both above loops were iterating over number by increasing or decreasing by 1, but, if we want to iterate by an arbitrary step i.e. not equals to 1. We can use step() function.

for (x in 1..10 step 2) {
	print(x)
}

Output

For reverse order

for (x in 9 downTo 0 step 3) {
	print(x)
}

Output

Example: Print Numbers in a Range Excluding Last Statement

And, if we do not want to include the last element from the range, we can use until() function.

for(i in 5 until 10){
	print(i)
}

Output

program

/**
 * Created by Aman gautam on 26-Nov-17.
 */
 
fun main(args : Array<String>){
    for(i in 1..5) {
        print(i)
    }
    println()
    for(i in 5 downTo 1){
        print(i)
    }
    println()
    for (x in 1..10 step 2) {
        print(x)
    }
    println()
    for (x in 9 downTo 0 step 3) {
        print(x)
    }
    println()
    for(i in 5 until 10){
        print(i)
    }
}