Programming · StudentHub Lesson

Loops

Learn how to repeat actions efficiently in code using for and while loops.

18 minBeginner

What you will learn

Differentiate between for and while loops
Use range() to control loop iterations
Write a while loop with a stopping condition
Avoid infinite loops
Use loops to process lists of data

Watch the lesson

Python for Beginners – Full Course [Programming Tutorial] · freeCodeCamp.org

Watch on YouTube

Topic notes

Main Idea

Loops let a program repeat a block of code multiple times without rewriting it.

Key Concepts

for loops iterate a fixed number of times or over a collection
while loops repeat as long as a condition remains true
range() generates a sequence of numbers for looping
Loops can be stopped early using break or skipped using continue

Definitions

Iteration: one full pass through a loop's code block
Infinite loop: a loop that never stops because its condition is always true
break: keyword that exits a loop immediately

Syntax

```python

for i in range(1, 6):

print(i)

count = 0

while count < 5:

print(count)

count += 1

```

Examples

Printing numbers 1 to 5 using a for loop
Repeating a prompt until valid input is given using a while loop

Common Mistakes

Forgetting to update the loop variable in a while loop, causing infinite loops
Off-by-one errors with range() bounds

Key concepts

for loopswhile loopsrange()break and continueinfinite loops

Important terms

Iteration: One complete pass through the body of a loop
Infinite loop: A loop whose condition never becomes false, causing it to run forever

Worked examples

Problem

Print 1 to 5 in Python

1. Use range(1,6)
2. for i in range(1,6): print(i)

Answer: 1 2 3 4 5

Quick revision

for loops iterate a known number of times
while loops repeat based on a condition
range(1,6) produces 1,2,3,4,5
break exits a loop early
Always update loop variables to avoid infinite loops

Check your understanding

Question 1 · Multiple choice

Which loop is best when you know exactly how many times to repeat?

Question 2 · Multiple choice

What does range(1, 4) produce?

Question 3 · True or false

A while loop can run forever if its condition never becomes false.

Question 4 · Short answer

What keyword immediately exits a loop?

Question 5 · Short answer

Write a loop condition to repeat while a variable x is less than 10.

Done with Loops?

Conditionals Functions