Which loop guarantees the loop body runs at least once before the condition is checked?

Which loop guarantees the loop body runs at least once before the condition is checked?

• A. While loop
• B. For loop
• C. Repeat until loop
• D. Do-While loop

Answer: (D)

This tests understanding of post-test loops, where the loop condition is checked after the loop body runs. In a do-while loop, you execute the body first and then check the condition. Because the body is performed before any check, you are guaranteed that the loop runs at least once, no matter what the condition is initially. In contrast, pre-test loops check the condition before executing the body, so the loop may not run at all if the condition is false from the start. A repeat-until variant is also post-tested in many languages, but the standard example used to illustrate this guarantee is the do-while loop, which is why it’s the correct choice here.

This tests understanding of post-test loops, where the loop condition is checked after the loop body runs. In a do-while loop, you execute the body first and then check the condition. Because the body is performed before any check, you are guaranteed that the loop runs at least once, no matter what the condition is initially.

In contrast, pre-test loops check the condition before executing the body, so the loop may not run at all if the condition is false from the start. A repeat-until variant is also post-tested in many languages, but the standard example used to illustrate this guarantee is the do-while loop, which is why it’s the correct choice here.