[已解决]求大佬帮我瞅瞅我快哭了

英俊男孩建坤

guests = ['a','b','c']
print (guests)
print ("hello "+guests[0]+" welcome")
guests[1]="d"
print (guests)
# [a d c]
print ("b can not attend.")
guests.append('e')
#[a d c e]
print(guests)
print("welcome "+guests[0]+" attend my this party!")
print("welcome "+guests[1]+" attend my this party!")
print("welcome "+guests[2]+" attend my this party!")
print("welcome "+guests[3]+" attend my this party!")
print("i find a big table,so we change the place")
guests.insert(0,'f')
#[f a d c e]
guests.insert(2,'g')
#[f a g d c e]
print(guests)
print('i am so sorry ,i only can invite two.')
first = guests.pop(0)
print ("sorry "+guests.pop(0))
#sorry f
second = guests.pop(1)
print ("sorry "+guests.pop(1))
#sorry a
third = guests.pop(2)
print ("sorry "+guests.pop(2))
#sorry g
forth = guests.pop(3)
print ("sorry "+guests.pop(3))
#sorry d
print(guests)
print(guests[0]+" welcome")
#c welcome
print(guests[1]+" welcome")
#e welcome
#最后我想把列表清空
del guests[0]
del guests[1]
print(guests)


说明一下 #后面的是我预想的结果 但是一运行就出问题了
显示这个     跟我预想的完全不同
['a', 'b', 'c']
hello a welcome
['a', 'd', 'c']
b can not attend.
['a', 'd', 'c', 'e']
welcome a attend my this party!
welcome d attend my this party!
welcome c attend my this party!
welcome e attend my this party!
i find a big table,so we change the place
['f', 'a', 'g', 'd', 'c', 'e']
i am so sorry ,i only can invite two.
sorry a
sorry c
Traceback (most recent call last):
  File "C:/Users/hp/Desktop/comp1002/自学/invitation.py", line 28, in <module>
    third = guests.pop(2)
IndexError: pop index out of range

最佳答案

月排行榜 / 总排行榜

heidern0612

2020-9-27 09:06:04

因为你pop了两遍。first一遍pop，打印一遍pop。 正确的应该是

print ("sorry "+first)

并且这种pop完了之后，列表的下标完全都变了，5个元素变成4个元素，原来的1下标变成了0下标，导致你后面index超过列表长度了。

跳转到最佳答案楼层

suchocolate

到这行【third = guests.pop(2)】的时候guests列表已经没有第2个元素了。

heidern0612

因为你pop了两遍。first一遍pop，打印一遍pop。 正确的应该是

print ("sorry "+first)

并且这种pop完了之后，列表的下标完全都变了，5个元素变成4个元素，原来的1下标变成了0下标，导致你后面index超过列表长度了。