Loops

for iterates over iterables; while loops while true.

Range & Enumerate

range(stop), range(start, stop, step), enumerate()

Break & Continue

break exits; continue skips iteration.

Syntax

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for i in range(5): print(i)
for i, v in enumerate(["a","b"]): print(i, v)
for i in range(10):
    if i == 3: continue
    if i == 7: break
    print(i)

Python Loops

PYTHON

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# For loop
for i in range(1, 6):
    print("Count:", i)

# While loop
count = 0
while count < 3:
    print("While:", count)
    count += 1

# Loop over collection
fruits = ["apple", "banana", "cherry"]
for index, fruit in enumerate(fruits):
    print(f"{index}: {fruit}")

# Continue / break
for n in range(1, 10):
    if n % 2 == 0:
        continue
    if n > 7:
        break
    print("Odd:", n)

Try It Yourself

Practice

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Exercise

Find all primes 1-50.

Answer

for n in range(2,51):
    if all(n%i for i in range(2,int(n**0.5)+1)):
        print(n, end=" ")

Quick Quiz

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When does the for-loop else execute?

Always

On break

Without break

Never

Else runs when loop completes without break.

Retry Quiz

Interview Questions

for vs while?

for for known iterations/sequences, while for condition-based unknown counts.

Previous

Conditionals

Tutorial Complete

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