How to Use Step in Kotlin: Syntax and Examples

In Kotlin, step is used with ranges or progressions to specify the increment between values in a loop or sequence. You add step(n) after a range to increase by n instead of the default 1.

Syntax

The step function is used with ranges or progressions to define the increment between values. The general syntax is:

start..end step increment

Here:

• start..end defines the range of values.
• step increment sets how much to increase each time.

kotlin

for (i in 1..10 step 2) {
    println(i)
}

Output

1
3
5
7
9

Example

This example shows how to print numbers from 1 to 10, increasing by 2 each time using step. It skips every other number.

kotlin

fun main() {
    for (i in 1..10 step 2) {
        println(i)
    }
}

Output

1
3
5
7
9

Common Pitfalls

One common mistake is forgetting that step only works with ranges or progressions, not with plain lists. Also, using a step value of 0 or negative numbers without proper direction causes errors or unexpected behavior.

Another pitfall is using step with a decreasing range without specifying downTo.

kotlin

fun main() {
    // Wrong: step with a list (won't compile)
    // val list = listOf(1, 2, 3, 4, 5)
    // for (i in list step 2) { println(i) }

    // Correct: use step with a range
    for (i in 5 downTo 1 step 2) {
        println(i)
    }
}

Output

5
3
1

Quick Reference

Usage	Description
start..end step n	Range from start to end, increment by n
start downTo end step n	Range from start down to end, decrement by n
step value must be > 0	Step must be positive to avoid errors
Works only with ranges/progressions	Cannot use step directly on lists

Key Takeaways

Use step with ranges to control the increment in loops.

Always ensure the step value is positive and matches the range direction.

step does not work on lists; use it only with ranges or progressions.

For decreasing sequences, combine downTo with step.

Using step helps skip values easily in loops.