python中pop()函数的语法与实例

语法：

列表 list.pop(obj=list[-1])
pop()用于删除并返回列表中的一个元素（默认为最后一个元素）

obj：要删除并返回的列表元素

字典dict.pop(key[,default])
pop()用于删除字典中给定的key及对应的value，返回被删除key对应的value，key值必须给出。给定的key值不在字典中时，返回default值。

key:需要删除的key值（不给出会报错）

default:若没有字典中key值，返回default值（给定的key值不在字典中时必须设置，否则会报错）

实例：

列表

>>> list1 = [1,2,4,"hello","xy","你好"]
>>> a = list1.pop()#默认弹出最后一个元素
>>> print(a，list1)
你好 [1,2,4,"hello","xy"]

>>> list2 = [1,2,4,"hello","xy","你好"]
>>> b = list2.pop(3)#弹出列表中第四个元素
>>> print(b,list2)
hello [1,2,4,"xy","你好“]

字典

>>> dict1 = {"papa":"xy","sis":"nikki","dude":"cwy"}
>>> c = dict.pop()#不给定key值报错
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")#给定键不在字典内时，未设置default值报错
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","不在字典内")
>>> print(d,dict2)
不在字典内 {'papa': 'xy', 'sis': 'nikki', 'dude': 'cwy'}

总结