Explain in detail the differences between Iterator and Iterable in Python

In Python, list, truple, str, dict can all be iterated, but they are not iterators. Why is that?

Because and iterators that have a quite different, list/truple/map/dict the size of the data is certain, that is to say how many things unknown. But the iterator is not. The iterator does not know how many times it will be executed, so it can be interpreted as not knowing how many elements there are. Every time next() is called once, it will go down 1 step, which is lazy.

To determine if you can iterate, use Iterable

from collections import Iterable
isinstance({}, Iterable) --> True
isinstance((), Iterable) --> True
isinstance(100, Iterable) --> False

To determine if it is an iterator, use Iterator

from collections import Iterator
isinstance({}, Iterator) --> False
isinstance((), Iterator) --> False
isinstance( (x for x in range(10)), Iterator) --> True

So,

Anything that can be for is Iterable

Anything that can next() is Iterator

Collection data types such as list, truple, dict, str are all Itrable not Iterator, but one Iterator object can be obtained through the iter() function

The for loop in Python is implemented through next

for x in [1,2,3,4,5]:
 pass

Is equivalent to

# First get iterator object 
it = iter([1,2,3,4,5])
while True:
 try:
  # To obtain the 1 A value 
  x = next(it);
 except StopIteration:
  #  encounter StopIteration Just exit the loop 
  break