The while loop

The while loop repeats a block, while its conditional expression returns true:

    while (condition) { 
        //code 
    } 

There is also a do... while loop that repeats blocks as long as a conditional expression is returning true:

    do { 
        //code 
    } while (condition)  

Kotlin, as opposed to Java, can use variables declared inside the do... while loop as a condition:

    do { 
        var found = false 
        //.. 
    } while (found) 

The main difference between the while and do... while loops is when a conditional expression is evaluated. A while loop checks the condition before code execution and if it is not true, the code won't be executed. On the other hand, a do... while loop first executes the body of the loop, and then evaluates the conditional expression, so the body will always execute at least once. If this expression is true, the loop will repeat. Otherwise, the loop terminates.