生成器相关的面试题

Posted 2022-04-27 zhuzl

def demo():
    for i in range(4):
        yield i

g=demo()

g1=(i for i in g)
g2=(i for i in g1)

print(list(g1))
print(list(g2))

运行结果：

[0, 1, 2, 3]
[]

View Code

 

面试题2

def add(n,i):
    return n+i

def test():
    for i in range(4):
        yield i

g=test()
for n in [1,10]:
    g=(add(n,i) for i in g)

print(list(g))

运行结果

[20, 21, 22, 23]

View Code

 讲解：上述代码中：

for n in [1,10]:
    g=(add(n,i) for i in g)

此for循环可写成：

n = 1
g=(add(n,i) for i in g)
n = 10
g=(add(n,i) for i in g)

def add(n,i):
    return n+i

def test():
    for i in range(4):
        yield i

g=test()

# for n in [1,10]:
#     g=(add(n,i) for i in g)

n = 1
g=(add(n,i) for i in g)
n = 10
g=(add(n,i) for i in g)

print(list(g))

当程序运行到print(list(g))语句时，程序才开始执行。

首先找g，找到g后逐一替换