What are Python generators and how are they used?

Question

Assisting AI · Accepted Answer

A generator is a special type of iterator that yields values one at a time and generates them on the fly, rather than computing all values upfront. It is defined using a function with the yield keyword or a generator expression. Generators are memory‑efficient for large data streams, allow lazy evaluation, and can maintain state between yields. They are commonly used for reading large files line by line, streaming data, or implementing infinite sequences. Example:

python

def countdown(n):
    while n > 0:
        yield n
        n -= 1

Iterating over countdown(5) produces 5,4,3,2,1 without storing the entire list.

```python
def countdown(n):
    while n > 0:
        yield n
        n -= 1
```

Iterating over `countdown(5)` produces 5,4,3,2,1 without storing the entire list.

What are Python generators and how are they used?

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