限制 Python 列表的长度
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Limit the length of a Python list
提问by Waheed Hussain
How would I set a list that only holds up to ten elements?
我将如何设置一个最多包含十个元素的列表？
I'm obtaining input names for a list using the following statement:
我正在使用以下语句获取列表的输入名称：
ar = map(int, raw_input().split())
and would like to limit the number of inputs a user can give
并希望限制用户可以提供的输入数量
回答by Moinuddin Quadri
After getting the arlist, you may discard the remaining items via list slicingas:
获取ar列表后，您可以通过列表切片丢弃剩余的项目：
ar = ar[:10] # Will hold only first 10 nums
In case you also want to raise error if list has more items, you may check it's length as:
如果您还想在列表有更多项目时引发错误，您可以检查它的长度为：
if len(ar) > 10:
raise Exception('Items exceeds the maximum allowed length of 10')
Note:In case you are making the length check, you need to make it before slicing the list.
注意：如果您要进行长度检查，则需要在对列表进行切片之前进行检查。
回答by CopyPasteIt
I found this post with a google search.
我通过谷歌搜索找到了这篇文章。
Yes, the following just expands on Moinuddin Quadri's answer (which I upvoted), but heck, this is what works for my requirements!
是的，以下只是扩展了 Moinuddin Quadri 的答案（我赞成），但是哎呀，这就是我的要求！
Python Program
蟒蛇程序
def lifo_insert(item, da_mem_list):
da_mem_list.insert(0, item)
return da_mem_list[:3]
# test
lifo_list = []
lifo_list = lifo_insert('a', lifo_list)
print('1 rec:', lifo_list)
lifo_list = lifo_insert('b', lifo_list)
lifo_list = lifo_insert('c', lifo_list)
print('3 rec:', lifo_list)
lifo_list = lifo_insert('d', lifo_list)
print('ovflo:', lifo_list)
OUTPUT
输出
1 rec: ['a']
3 rec: ['c', 'b', 'a']
ovflo: ['d', 'c', 'b']
回答by sidshrivastav
You can also do something like this.
你也可以做这样的事情。
n = int(input())
a = [None] * n
It will create a list with limit n.
它将创建一个限制为 n 的列表。
