What is the use of iter in python?

问题:

What is the use of using the iter function in python?

Instead of doing:

for i in range(8):
  print i

I could also use iter:

for iter in range(8):
  print iter

回答1:

First of all: iter() normally is a function. Your code masks the function by using a local variable with the same name. You can do this with any built-in Python object.

In other words, you are not using the iter() function here. You are using a for loop variable that happens to use the same name. You could have called it dict and it would be no more about dictionaries than it is about Guido's choice of coffee. From the perspective of the for loop, there is no difference between your two examples.

You'd otherwise use the iter() function to produce an iterator type; an object that has a .next() method (.__next__() in Python 3).

The for loop does this for you, normally. When using an object that can produce an iterator, the for statement will use the C equivalent of calling iter() on it. You would only use iter() if you were doing other iterator-specific stuff with the object.

回答2:

iter() is a Python built-in function that returns an iterator object, which is an object that represent some data. For example, it could be used with a .next() method on the iterator that will give you the next element - StopIteration will occur when there are no more elements.