Ranges and loops in Kotlin

Ranges are values, and for iterates anything that provides one.

fun main() {
    // Ranges are values: 1..5 includes both ends; downTo and step
    // reshape the walk without an index variable in sight.
    for (km in 1..5) print("$km ")
    println()
    for (switchback in 10 downTo 6) print("$switchback ")
    println()
    for (marker in 0..20 step 5) print("$marker ")
    println()

    var water = 3
    while (water > 0) {
        water -= 1
    }
    println("Bottles left: $water")
}

How it works

1..5 includes both ends; the loop variable needs no declaration.
10 downTo 6 runs backward and 0..20 step 5 skips.
while is the classic guard loop for the cases ranges cannot express.

Keywords and builtins used here

for
fun
in
main
var
while

The run, in numbers

Lines: 16
Characters to type: 375
Tokens: 90
Three-star pace: 70 tpm

At the three-star pace of 70 tokens a minute, this run takes about 77 seconds.

Type this snippet

Step 3 of 3 in Control flow, step 6 of 27 in Language basics.

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Ranges and loops in other languages

Swift