do-while Loop in Kotlin

What Is a do-while Loop?

A do-while loop is a control structure that lets you repeat a block of code as long as a certain condition is true. The key feature of the do-while loop is that it always runs the code inside the loop at least once, even if the condition is false from the start.

How a do-while Loop Works

The do-while loop has two main parts:

• The do block, where you put the code you want to repeat;
• The while condition, which is checked after the code runs each time.

The basic structure looks like this:

var counter = 1

do {
    println("Counter is $counter")
    counter++
} while (counter <= 5)

This loop prints the numbers 1 through 5. The code inside the do block runs, then the loop checks if counter is still less than or equal to 5. If it is, the loop runs again.

How Is do-while Different from while?

The main difference between a do-while loop and a while loop is when the condition is checked:

• do-while loop: runs the block once, then checks the condition; always executes the code at least once;
• while loop: checks the condition first; if the condition is false, the code inside the loop may never run.

This makes the do-while loop useful when you want to guarantee the code runs at least one time, such as when asking a user for input until they provide a valid answer.