iter()内置函数

将对象传入iter, 会自动生成__next__()方法, 对象变为可迭代的. 迭代方法:

1. next()内置函数
2. obj.__next__()对象方法

L = [1, 2, 3]

I = iter(L)

print(I.__next__())
print(I.__next__())
print(next(I))

上述代码等价于:

for i in L:
    print(i)

或者:

while True:
    try:
        x = I.__next__()
    except StopIteration:
        break
    print(x)