2 Python Iterators

1. What is an Iterator?

An iterator is an object that lets us go through values one by one.

In simple words:
👉 An iterator remembers where it is
👉 It gives one value at a time
👉 It stops when values are finished

2. Real-Life Example (Easy)

Think of a TV remote 📺

• Next button → next channel

• One channel at a time

Iterator works the same way.

3. Iterable vs Iterator (Important)

Iterable

Something you can loop over
Examples:

• list

• tuple

• string

• set

Iterator

The object that actually gives values one by one

4. Simple Iterator Example (List)

Example

Output:

5. What are iter() and next()?

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  iter() → creates an iterator   next() → gets next value

  
   

6. Iterator Stops Automatically

When items finish, Python raises StopIteration.

Example

7. Iterator with Loop (Easy Way)

We normally use for loop, Python handles iterator automatically.

Example

👉 Behind the scenes, Python uses iterator.

8. Iterator with String

Example

9. Creating Your Own Iterator (Basic)

To create your own iterator, you need:

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  __iter__()   __next__()

  
   

Example

10. Iterator vs Generator (Simple Difference)

👉 Generators are easier (we learned them before).

11. Common Beginner Mistakes

❌ Calling next() Too Many Times

❌ Error when values finish.

❌ Forgetting iter()

✔ Correct:

12. Simple Practice Examples

Example 1: Iterate Tuple

Example 2: Iterate String with Loop

Example 3: Manual Iterator

13. When Should You Use Iterators?

✔ When working with large data
✔ When memory saving is important
✔ When values come step by step

14. Summary (Python Iterators)

✔ Iterator gives values one by one
✔ Uses iter() and next()
✔ Stops with StopIteration
✔ for loop uses iterator internally
✔ Important concept in Python

📘 Perfect for Beginner eBook

This chapter is ideal for:

• Python beginner books

• School & college students

• Self-learners

If you want next, I can write:

• Iterator vs Generator (full)

• Comprehensions

• Exception Handling

• File Handling

• Mini Python Projects

Just tell me 😊