26：迭代器和生成器
x='hello' print(dir(x)) iter_test=x.__iter__()
print(iter_test) print(iter_test.__next__()) print(iter_test.__next__()) print(iter_test.__next__()) print(iter_test.__next__()) print(iter_test.__next__()) print(iter_test.__next__())
l=[1,2,3]
for i in l: #i_l=l.__iter_() i_l.__next__()
print(i)
index=0
while index < len(l):
print(l[index])
index+=1
iter_l=l.__iter__() #遵循迭代器协议，生成可迭代对象 print(iter_l.__next__()) print(iter_l.__next__())
for i in l:
print(i)
s={1,2,3}
for i in s:
print(i)
iter_s=s.__iter__()
print(iter_s)
print(iter_s.__next__())
print(iter_s.__next__())
print(iter_s.__next__())
print(iter_s.__next__())
dic={'a':1,'b':2}
iter_d=dic.__iter__()
print(iter_d.__next__())
f=open('test.txt','r+')
# for i in f:
iter_f=f.__iter__()
print(iter_f)
print(iter_f.__next__(),end='')
print(iter_f.__next__(),end='')
l=[1,2,3,4,5]
diedai_l=l.__iter__()
while True:
try:
print(diedai_l.__next__())
except StopIteration:
# print('迭代完毕了,循环终止了')
break
l=['die','erzi','sunzi','chongsunzi'] iter_l=l.__iter__() print(iter_l) print(iter_l.__next__()) print(iter_l.__next__()) print(iter_l.__next__()) print(iter_l.__next__()) print(iter_l.__next__()) print(next(iter_l)) #next()---->iter_l.__next__()
def test():
yield 1
yield 2
yield 3
g=test()
print('来自函数',g)
print(g.__next__())
print(g.__next__())
三元表达式
name='alex'
name='linhaifeng'
res='SB' if name == 'alex' else '帅哥'
print(res)
列表解析
egg_list=[]
for i in range(10):
egg_list.append('鸡蛋%s' %i)
print(egg_list)
l=['鸡蛋%s' %i for i in range(10)]
l1=['鸡蛋%s' %i for i in range(10) if i > 5 ]
# l1=['鸡蛋%s' %i for i in range(10) if i > 5 else i] #没有四元表达式
l2=['鸡蛋%s' %i for i in range(10) if i < 5] #没有四元表达式
print(l)
print(l1)
print(l2)
laomuji=('鸡蛋%s' %i for i in range(10)) #生成器表达式
print(laomuji)
print(laomuji.__next__())
print(laomuji.__next__())
print(next(laomuji))
print(next(laomuji))
print(next(laomuji))
print(next(laomuji))
print(next(laomuji))
print(next(laomuji))
print(next(laomuji))
print(next(laomuji))
print(next(laomuji))
l=[1,2,3,34] map(func,l) print(sum(l)) print(sum()) print(sum(i for i in range(10000000000000)))
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