python的iter函数怎么用(python __iter__用法)

生成迭代器。

>>> help(iter)

# output:
Help on built-in function iter in module builtins:

iter(...)
	## 使用方法：
    iter(iterable) -> iterator
    iter(callable, sentinel) -> iterator
    
    Get an iterator from an object.  In the first form, the argument must
    supply its own iterator, or be a sequence.
    In the second form, the callable is called until it returns the sentinel.

示例1.

next() 返回下一个迭代器对象.

>>> a = [0,1,2,3,4]
>>> a = iter(a)
>>> next(a), next(a), next(a)

# output:
(0, 1, 2)

示例2.

>>> a = [0,1,2,3,4]
>>> a = iter(a)
>>>
>>> for i in a:
>>>    print(i)

# output:
0
1
2
3
4