python入门 第十五天 生成器、迭代器

def xrange():
    print(11)
    yield 1
    print(22)
    yield 2
    print(33)
    yield 3
# 仅仅获取了一个生成器
r = xrange()
# 生成器的__next__方法，执行函数寻找下一个yield
ret = r.__next__()
print(ret) 
"""
11
1
"""
ret = r.__next__()
print(ret)
"""
22
2
"""
ret = r.__next__()
print(ret)
"""
33
3
"""
# xrange的内部实现原理
def myXrange(n):
    start = 0
    while True:
        if start > n:
            return 
        yield start
        start += 1
# =====================
# 创建迭代器
obj = myXrange(5)
n1 = obj.__next__()
n2 = obj.__next__()
n3 = obj.__next__()
n4 = obj.__next__()
n5 = obj.__next__()
n6 = obj.__next__()
print(n1, n2, n3, n4, n5, n6) # 1 2 3 4 5