Lesson 13 of 16 · 50 min · UG / professional

pass, early stop, and else on loops

pass is a legal empty body. break/continue are laptop spellings of ‘stop now’ and ‘skip this turn’. A loop’s else runs when you never stopped early — useful in a search that must report ‘not found’.

Roll-number search

Scan a list; sort a copy.

You will be able to

✓ Use pass as a legal empty body
✓ Model break/continue with a flag in this sandbox
✓ Know loop-else means ‘never stopped early’

pass, break, continue

pass does nothing — a placeholder for a function you will fill, or an empty class on a laptop. break leaves the innermost loop now. continue skips the rest of this turn. This teaching sandbox does not run break/continue; a flag (found = 1) is the same policy, visible in the code.

An else attached to for/while on a laptop runs when the loop finished normally — not after break. That is how a prime-search example reports ‘no factor found’. Here: if found == 0: print("Missing") after the loop.

Search vs filter

A search stops after the first hit. A filter keeps collecting. Do not mix them. continue is ‘this row is uninteresting’; break is ‘we are done’.

Laptop: break, continue, loop else

for n in range(2, 6):
    if n % 2 == 0:
        print("even", n)
        continue
    print("odd", n)
else:
    print("finished without break")

Words that matter

pass: A legal empty body.
break: Leave the loop now (laptop).
loop else: Runs if the loop was not broken (laptop).

Common mistakes

Avoid: Using pass as the only error handling.

Do this: pass is a placeholder, not a policy.

Run it step by step

Each box is a real program. Press Run, change a number, Run again — the output must follow your code.

1. Step 1 — pass as a stub

The function exists. Later you will fill it. Today it returns 0.

Python sandboxlesson://workspace

console

Edit the example, press Run, then Build if you want a compile check.

build

Press Build to compile.

2. Step 2 — first match, then ‘not found’

Flag stands in for break. Zero means loop-else energy.

Python sandboxlesson://workspace

console

Edit the example, press Run, then Build if you want a compile check.

build

Press Build to compile.

Example program — Stop after the first heat

34 is enough. The rest can wait.

Python sandboxlesson://workspace

console

Edit the example, press Run, then Build if you want a compile check.

build

Press Build to compile.

Your turn — Print Missing

codes = ["A", "B"]. Search for "Z". Print Missing when it is not there.

Python sandboxlesson://workspace

console

Edit the example, press Run, then Build if you want a compile check.

build

Press Build to compile.

Self-assessment

Check your understanding before you mark the lesson complete.

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