python中的pop()函式
語法：
串列
list.pop(obj=list[-1])
pop()用于洗掉并回傳串列中的一個元素（默認為最后一個元素）
- obj：要洗掉并回傳的串列元素
字典
dict.pop(key[,default])
pop()用于洗掉字典中給定的key及對應的value，回傳被洗掉key對應的value，key值必須給出，給定的key值不在字典中時，回傳default值，
- key:需要洗掉的key值（不給出會報錯）
- default:若沒有字典中key值，回傳default值（給定的key值不在字典中時必須設定，否則會報錯）
實體：
- 串列
>>> list1 = [1,2,4,"hello","xy","你好"]
>>> a = list1.pop()#默認彈出最后一個元素
>>> print(a，list1)
你好 [1,2,4,"hello","xy"]
>>> list2 = [1,2,4,"hello","xy","你好"]
>>> b = list2.pop(3)#彈出串列中第四個元素
>>> print(b,list2)
hello [1,2,4,"xy","你好“]
- 字典
>>> dict1 = {"papa":"xy","sis":"nikki","dude":"cwy"}
>>> c = dict.pop()#不給定key值報錯
Traceback (most recent call last):
File "<pyshell#2>", line 1, in <module>
c = dict.pop()
TypeError: unbound method dict.pop() needs an argument
>>> dict1 = {"papa":"xy","sis":"nikki","dude":"cwy"}
>>> c = dict1.pop("papa")
>>> print(c,dict1)
xy {'sis': 'nikki', 'dude': 'cwy'}
>>> dict2 = {"papa":"xy","sis":"nikki","dude":"cwy"}
>>> d = dict2.pop("www")#給定鍵不在字典內時，未設定default值報錯
Traceback (most recent call last):
File "<pyshell#15>", line 1, in <module>
d = dict2.pop("www")
KeyError: 'www'
>>> dict2 = {"papa":"xy","sis":"nikki","dude":"cwy"}
>>> d = dict2.pop("www","不在字典內")
>>> print(d,dict2)
不在字典內 {'papa': 'xy', 'sis': 'nikki', 'dude': 'cwy'}
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標籤：python
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