Loops Cheatsheet

First PublishedFeb 10, 2026ByAtif Alam

for over a list

for fruit in ['apple', 'banana', 'cherry']:
    print(fruit)

With index using enumerate:

fruits = ['apple', 'banana', 'cherry']
for index, fruit in enumerate(fruits):
    print(index, fruit)  # 0 apple, 1 banana, 2 cherry

for with range

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

for i in range(1, n):     # 1 .. n-1 (e.g. split between i-1 and i)
    ...

for over a string

for char in "hello":
    print(char)  # h, e, l, l, o

for over a dictionary

person = {'name': 'Alice', 'age': 30}

# Keys only
for key in person:
    print(f"Key: {key}")

# Keys and values
for key, value in person.items():
    print(f"{key} → {value}")

# Keys in sorted order
for key in sorted(person):
    print(key)

Parallel iteration with zip

names = ['Alice', 'Bob']
scores = [85, 92]

for name, score in zip(names, scores):
    print(f"{name} scored {score}")

Reading a file line by line

with open(filename, 'r') as file:
    for line in file:
        print(line.rstrip())  # or process line

while loop

count = 0
while count < 3:
    print("Count:", count)
    count += 1