Python’s iter() Function

• object: The object to be converted into an iterator.
• sentinel (optional): A value that, if provided, is used to stop iteration.

Example 1: Basic Usage

Let’s start with a simple example:

my_list = [1, 2, 3, 4, 5]
my_iter = iter(my_list)
print(next(my_iter))  # Output: 1
print(next(my_iter))  # Output: 2

Here, we create an iterator from a list using iter(). We then use the next() function to iterate through the elements of the list.

Example 2: Using iter() with Custom Objects

You can also use iter() with custom objects by implementing the __iter__() method:

class MyIterator:
    def __init__(self, max_limit):
        self.max_limit = max_limit
        self.current = 0
    def __iter__(self):
        return self
    def __next__(self):
        if self.current < self.max_limit:
            self.current += 1
            return self.current
        else:
            raise StopIteration

my_iter = iter(MyIterator(5))

for num in my_iter:
    print(num)

In this example, we define a custom iterator class MyIterator, which generates numbers up to a maximum limit. We then use iter() to create an iterator from an instance of this class and iterate through it using a for loop.

Example 3: Using iter() with a Callable Sentinel

You can also use a callable as a sentinel value to stop iteration:

import random
def random_generator():
    while True:
        num = random.randint(1, 100)
        yield num
        if num == 50:
            break
random_iter = iter(random_generator(), 50)
for num in random_iter:
    print(num)

Here, we create a generator function random_generator() that yields random numbers. We then use iter() with a callable sentinel (random_generator()) and stop iteration when the generated number equals 50.

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