is for/while loop from python is a generator

Question

In an interview , the interviewer asked me for some of generators being used in Python. I know a generator is like a function which yield values instead of return.

so any one tell me is for/while loop is an example of generator.

Answer 1

Short answer: No, but there are other forms of generators.

A for/while loop is a loop structure: it does not emit values and thus is not a generator.

Nevertheless, there are other ways to construct generators.

You example with yield is for instance a generator:

def some_generator(xs):
    for x in xs:
        if x:
            yield x

But there are also generator expressions, like:

(x for x in xs if x)

Furthermore in python-3.x the range(..), map(..), filter(..) constructs are generators as well.

And of course you can make an iterable (by using an iterable pattern):

class some_generator(object):
    def __init__(self, xs):
        self.n = n
        self.idx = 0

    def __iter__(self):
        return self

    def __next__(self):
        return self.next()

    def next(self):
        while self.num < len(self.xs) and not self.xs[self.num]:
            self.num += 1
        if self.num < len(self.xs):
            res = self.xs[self.num]
            self.num += 1
            return res
        else:
            raise StopIteration()

Answer 2

Neither while nor for are themselves generators or iterators. They are control constructs that perform iteration. Certainly, you can use for or while to iterate over the items yielded by a generator, and you can use for or while to perform iteration inside the code of a generator. But neither of those facts make for or while generators.