for Loops

What You Will Learn

Loops let you repeat code without writing it over and over. The for loop is the most common loop in Python.

Your First for Loop

for i in range(5):
    print(i)

Expected output:

0
1
2
3
4

range(5) generates the numbers 0, 1, 2, 3, 4. The variable i takes each value in turn. The indented code runs once for each value.

range() Options

# range(stop) — 0 up to (but not including) stop
for i in range(5):
    print(i)  # 0, 1, 2, 3, 4

# range(start, stop)
for i in range(2, 6):
    print(i)  # 2, 3, 4, 5

# range(start, stop, step)
for i in range(0, 10, 2):
    print(i)  # 0, 2, 4, 6, 8

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

Looping Over a List

fruits = ["apple", "banana", "cherry"]

for fruit in fruits:
    print(fruit)

Expected output:

apple
banana
cherry

You will learn more about lists in a later lesson. For now, just know that a for loop can go through any collection of items.

Looping Over a String

word = "Python"

for letter in word:
    print(letter)

Expected output:

P
y
t
h
o
n

Using the Loop Variable

for i in range(1, 6):
    print(f"{i} x 3 = {i * 3}")

Expected output:

1 x 3 = 3
2 x 3 = 6
3 x 3 = 9
4 x 3 = 12
5 x 3 = 15

Accumulating a Result

A common pattern is to start with a value and build it up inside a loop:

total = 0

for i in range(1, 6):
    total = total + i
    print(f"Added {i}, total is now {total}")

print(f"Final total: {total}")

Expected output:

Added 1, total is now 1
Added 2, total is now 3
Added 3, total is now 6
Added 4, total is now 10
Added 5, total is now 15
Final total: 15

What You Learned

• for loops repeat code for each item in a sequence
• range() generates a sequence of numbers
• You can loop over lists, strings, and other collections
• Use the loop variable to access each item
• Accumulate results by updating a variable inside the loop

In the next lesson, you will learn about while loops — loops that repeat as long as a condition is true.