Custom Iterator

Implement a class that can be iterated over using __iter__ and __next__.

PythonIntermediate

Python

# Program to implement a custom iterator

class Countdown:
    def __init__(self, start):
        self.current = start

    def __iter__(self):
        return self

    def __next__(self):
        if self.current <= 0:
            raise StopIteration
        value = self.current
        self.current -= 1
        return value


for num in Countdown(3):
    print(num)

Output

3
2
1

By defining iter and next, Countdown becomes an iterator usable in for-loops.

Operator Overloading

Class Methods