When is the condition checked in a DO UNTIL loop?

In a DO UNTIL loop, the condition is evaluated after each iteration of the loop. This means that the code within the loop's body will execute at least once, regardless of the condition, because the check occurs only after the complete execution of the statements inside the loop. If the condition is not met after the first iteration, the loop will continue to run until the specified condition evaluates to true. This behavior distinguishes the DO UNTIL loop from other looping constructs, such as the DO WHILE loop, where the condition is evaluated before the execution of the loop's body.

The nuance in evaluating the condition after the iteration allows for scenarios where the processing or computations that happen within the loop might affect the condition itself, thus enabling more dynamic control of the loop's execution.