Unit 3 · Lesson 5

break, continue & Loop-Else

Sometimes you need to bail out of a loop early, or skip certain iterations. Python gives you three precise tools for fine-grained loop control.

Use break to exit a loop early

Use continue to skip iterations

Understand the for...else pattern

Choose the right tool for each situation

Three Loop Control Tools

🛑 break

Immediately exits the entire loop. Code after the loop runs next.

for i in range(10):
  if i == 5:
    break
# jumps here

⏭️ continue

Skips the rest of this iteration. Jumps back to the loop condition.

for i in range(5):
  if i == 2:
    continue
  print(i)
# 0,1,3,4

🔄 for...else

The else block runs only if the loop finished without hitting break.

for i in data:
  if found:
    break
else:
  print("not found")

break — The Emergency Exit

break is perfect when you're searching for something and want to stop as soon as you find it:

# Find the first even number numbers = [7, 3, 11, 8, 5, 2] for n in numbers: if n % 2 == 0: print(f"Found it: {n}") break # Output: Found it: 8

continue — Skip and Move On

continue skips the rest of the current iteration and jumps to the next one:

# Print only positive numbers for x in [3, -1, 4, -5, 9]: if x < 0: continue # skip negatives print(x) # Output: 3, 4, 9

for...else — "Did We Find It?"

Python's unique for...else pattern: the else block runs only if the loop completed without break. Perfect for search-and-report:

for i in range(2, num): if num % i == 0: print(f"{num} is NOT prime (divisible by {i})") break else: print(f"{num} IS prime!")

How for...else works: If the loop runs to completion (range exhausted, no break hit) → the else block runs. If break fires → the else block is skipped. Think of it as "if the loop didn't break."

Practice Time

Challenges

🔤

Challenge 1: First Vowel Finder

Guided

Find the first vowel in a word using break.

Instructions: Loop through each character in word. When you find a vowel (a, e, i, o, u — check lowercase), store it in first_vowel and break. If no vowel is found, first_vowel should stay "none".

Hint: Use for char in word: to iterate through characters.

Hint 1: for char in word: gives you each letter.
Hint 2: if char.lower() in "aeiou": checks if it's a vowel.
Hint 3: Inside the if: first_vowel = char then break

⏭️

Challenge 2: Positive Sum

Guided

Sum only the positive numbers from a list, using continue to skip negatives.

Instructions: Loop through numbers. Use continue to skip any negative values. Add positive values to total.

Hint 1: for n in numbers:
Hint 2: if n < 0: continue — skips to the next iteration
Hint 3: After the continue check: total += n

🔐

Challenge 3: Password Attempts

Solo

Simulate a login system with limited attempts using a loop with break.

Instructions: The correct password is secret. Loop through the attempts list. If a guess matches, set result to "Access granted" and break. If none match, result should be "Account locked".

Try using for...else for this!

Hint 1: for guess in attempts: — try each one
Hint 2: if guess == secret: result = "Access granted" then break
Hint 3: Use for...else: the else: block sets result = "Account locked" — it only runs if no break happened.

🔍

Challenge 4: Prime Finder

Stretch

Find all prime numbers up to limit using nested loops with for...else.

Instructions: For each number from 2 to limit, use an inner loop to check if it's prime. If no divisor is found (loop completes without break), it's prime — add it to the primes string. Separate primes with spaces.

Example: limit=20 → "2 3 5 7 11 13 17 19"

Hint 1: Outer: for num in range(2, limit + 1):
Hint 2: Inner: for i in range(2, num): — if num % i == 0: break
Hint 3: Add else: after the inner loop (aligned with inner for): primes += str(num) + " "