26：迭代器和生成器

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x='hello' print(dir(x)) iter_test=x.__iter__()

　

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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__())

　　

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l=[1,2,3] for i in l:  #i_l=l.__iter_()  i_l.__next__()     print(i)

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index=0 while index < len(l):     print(l[index])     index+=1

　

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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__())

　

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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__())

　　

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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

　　

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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__()

　

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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)

　

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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)

　　

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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))

　　

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l=[1,2,3,34] map(func,l)   print(sum(l)) print(sum()) print(sum(i for i in range(10000000000000)))