else — Intermediate Examples

Catch-all branch when preceding if/elif conditions are all false

EasyIntermediateAdvancedExpert

else with for and while loops

Loop else runs when the loop completes without break.

python
# for/else: check if a number is prime
def is_prime(n):
    if n < 2:
        return False
    for i in range(2, int(n**0.5) + 1):
        if n % i == 0:
            return False  # could use break + else here too
    return True

# Using for/else pattern
for n in [17, 18, 19, 20]:
    for i in range(2, n):
        if n % i == 0:
            print(f"{n} = {i} x {n//i}")
            break
    else:
        print(f"{n} is prime")
Expected Output
17 is prime
18 = 2 x 9
19 is prime
20 = 2 x 4

Loop else is unusual: it runs when the loop finishes normally (without break). Think of it as 'nobreak' — it runs if break was never hit.

else with try/except

Running code only when no exception occurred.

python
def safe_divide(a, b):
    try:
        result = a / b
    except ZeroDivisionError:
        print(f"Cannot divide {a} by zero")
    else:
        print(f"{a} / {b} = {result}")
    finally:
        print("---")

safe_divide(10, 3)
safe_divide(10, 0)
Expected Output
10 / 3 = 3.3333333333333335
---
Cannot divide 10 by zero
---

try/else runs only when no exception was raised. Put code here that should only run on success, keeping the try block minimal.

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