While Loop

While a for loop works great when you know the exact number of iterations, sometimes you need to keep looping until a certain condition changes. That's where the while loop comes in.

A while loop continues running as long as its condition is true:

var count = 1
while (count <= 3) {
    println(count)
    count++
}
// Output:
// 1
// 2
// 3

The loop checks the condition before each iteration. Once count becomes 4, the condition count <= 3 is false, and the loop stops.

Be careful: if the condition never becomes false, you'll create an infinite loop. Always make sure something inside the loop eventually changes the condition:

var password = ""
while (password != "secret") {
    password = readLine() ?: ""
}
println("Access granted!")

This loop keeps asking for input until the user enters "secret". The while loop is ideal when you don't know in advance how many iterations you'll need.