KOTLIN Tutorial

Loops in Kotlin

Loops are used to execute a block of code multiple times. Kotlin provides several loop types to handle repetitive tasks efficiently.

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1. for Loop

The for loop is used to iterate over ranges, arrays, or collections.

fun main() {
    for (i in 1..5) {
        println("Count: $i")
    }
}
  

Output:
Count: 1
Count: 2
... up to 5

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2. while Loop

Repeats a block of code while a condition is true.

fun main() {
    var x = 1
    while (x <= 3) {
        println("x is $x")
        x++
    }
}
  

Output:
x is 1
x is 2
x is 3

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3. do...while Loop

This loop executes the block at least once before checking the condition.

fun main() {
    var y = 1
    do {
        println("y is $y")
        y++
    } while (y <= 2)
}
  

This will print y is 1 and y is 2.

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4. Looping Through Arrays

Iterate directly through elements of a list or array.

fun main() {
    val fruits = listOf("Apple", "Banana", "Cherry")

    for (fruit in fruits) {
        println(fruit)
    }
}
  

Output:
Apple
Banana
Cherry

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5. Loop with Index

You can get both element and index using withIndex().

fun main() {
    val colors = arrayOf("Red", "Green", "Blue")

    for ((index, value) in colors.withIndex()) {
        println("Index $index: $value")
    }
}
  

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6. Breaking & Continuing

Use break to exit a loop and continue to skip an iteration.

fun main() {
    for (i in 1..5) {
        if (i == 3) continue
        if (i == 5) break
        println(i)
    }
}
  

Output: 1, 2, 4 (3 is skipped, loop breaks at 5)

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Summary

• for — iterate over ranges, arrays
• while — repeat while a condition is true
• do...while — always runs at least once
• break / continue — control the loop flow