What is the role of the yield operator in Python, and how does it affect function execution?

The yield operator in Python is used inside functions to create generators — special iterators that return values one at a time, maintaining their state between calls.

When a function with yield is called, it does not execute fully but returns a generator. Each time the __next__() method is called, the generator resumes execution of the function until the next yield, returning a value and pausing execution.

This allows efficient handling of large volumes of data without loading it entirely into memory.

Example:

def count_up_to(n):
    count = 1
    while count <= n:
        yield count
        count += 1

for number in count_up_to(5):
    print(number)

In this example, the count_up_to function returns numbers from 1 to n one at a time using yield. This saves memory and allows processing data as needed.