???? ???? ???? ?
???? ?????? ????? ?? ??? ???? ??? ?? ?? ???? ?? ???? ???
1. ??? ??
??? ??? ???? ???? ?? ?? ?? ?? ??? ????. ?? ?? ??,
list1 = [1,2,3,4,5] for num1 in list1 : print ( num1 , end = ' ' )
1?? 5??. ??? 5?? 1?? ??? ?? ???? ??? ?? ?????. Python
list1 = [1,2,3,4,5] for num1 in reversed(list1) : print ( num1 , end = ' ' )
?? ?? reversed()? ????. ?? ??? ?? ?????, ? ?? ??? ?? ? ??? ??? ??? ?? ??? ? ??? ??? ?? ?? ????? ????. __reversed__()? ?? ???? ???? ?????. ? ? ???? ??? ?? ??? ???? ???? ???. ??? ??? ?? ???? __reversed__() ???? ???? ??? ??? ??? ? ?? ??? ????. ??? ?? ???? ?? ?? ??? ???? ???? ????? ??? ?? ???? ?? ?? ??? ??? ? ??? ? ?? ????.
# -*- coding: UTF-8 -*- class Countdown: def __init__(self, start): self.start = start def __iter__(self): # Forward iterator n = self.start while n > 0: yield n n -= 1 def __reversed__(self): # Reverse iterator n = 1 while n <= self.start: yield n n += 1 for rr in reversed(Countdown(30)): print(rr) for rr in Countdown(30): print(rr)
?? ??? 1~30, 30~1? ?? ?? ??? ??? ?????
2 ??? ?? ???? ??????? ???? ??? ???? ????. ?? ??? ????? ??? ?????. ?? ???? ?? ?? ?????
?? ???? ??? ????? zip() ??? ?????. ???? ?:
# -*- coding: UTF-8 -*- names = ['laingdianshui', 'twowater', '兩點(diǎn)水'] ages = [18, 19, 20] for name, age in zip(names, ages): print(name,age)
?? ??:
laingdianshui 18 twowater 19 兩點(diǎn)水 20
??? zip(a, b)? ??( x, y) , ??? x? a?? ??? y? b?? ????. ??? ? ??? ?? ???? ??? ?????. ??? ?? ??? ?????? ?? ?? ???? ??? ?????. ? ??? ????? ?????. ?, a? b? ??? ???? ??? ?? ?? ?? ???? ?? ??? ?????.
zip() ??? ???? ??? ?? ? ??? ? ???? dict(??)? ??? ?? ????.
# -*- coding: UTF-8 -*- names = ['laingdianshui', 'twowater', '兩點(diǎn)水'] ages = [18, 19, 20] dict1= dict(zip(names,ages)) print(dict1)
?? ??? ?????.
{'laingdianshui': 18, 'twowater': 19, '兩點(diǎn)水': 20}
??? zip()? ? ? ?? ?? ???????. ? ?? ?? ? ? ??? ??? ????? ?????.