while Loops, break and continue
Try it: while Loops, break and continue
How a while loop re-evaluates its condition before every pass, how break leaves the loop at once, how continue jumps back to the condition, how a sentinel value ends a while True loop, and why a loop whose condition never becomes False runs forever.
How it works
- Evaluate the condition. If it is False, skip the body and continue after the loop.
- If it is True, run the body from the top, then go back and evaluate the condition again.
- continue skips the rest of the body and goes straight back to the condition check.
- break leaves the loop immediately; the condition is not checked again (while True loops rely on it, e.g. stopping at a sentinel like 'done').
- If nothing in the body can make the condition False, the loop never ends; the lab's guard stops it after N iterations and says so.
Default run (21 steps): Ready: Countdown. A while loop checks its condition before every pass. … Finished after 5 iterations and 6 condition checks.
Simplified: The lab's own small Python interpreter runs a fixed, hand-written script (you choose the variant and the values, never the code); nothing is executed as real Python. Every script was run in CPython 3.12 with the same inputs and the lab reproduces its output and error messages. input() returns the lines you type in the list, one per call (the prompt is not printed), and raises EOFError when they run out, like a closed keyboard stream. The guard is the lab's, not Python's.
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