我想异常处理“列表索引超出范围".

问题描述

我正在使用 BeautifulSoup 并解析一些 HTML.

I am using BeautifulSoup and parsing some HTMLs.

我从每个 HTML 中获取特定数据 (使用 for 循环) 并将该数据添加到特定列表中.

I'm getting a certain data from each HTML (using for loop) and adding that data to a certain list.

问题是，一些 HTML 具有不同的格式(并且它们没有我想要的数据).

The problem is, some of the HTMLs have different format (and they don't have the data that I want in them).

所以，我试图使用异常处理并将值 null 添加到列表 (我应该这样做，因为数据的顺序很重要.)

So, I was trying to use exception handling and add value null to the list (I should do this since the sequence of data is important.)

例如，我有一个类似的代码:

For instance, I have a code like:

soup = BeautifulSoup(links)
dlist = soup.findAll('dd', 'title')
# I'm trying to find content between <dd class='title'> and </dd>
gotdata = dlist[1]
# and what i want is the 2nd content of those
newlist.append(gotdata)
# and I add that to a newlist

而且有些链接没有任何<dd class='title'>，所以我想做的是将字符串 null 添加到改为列出.

and some of the links don't have any <dd class='title'>, so what I want to do is add string null to the list instead.

出现错误:

list index out of range.

我所做的尝试是添加一些这样的行:

What I have done tried is to add some lines like this:

if not dlist[1]:
   newlist.append('null')
   continue

但是没有用.它仍然显示错误:

But it doesn't work out. It still shows error:

list index out of range.

我该怎么办?我应该使用异常处理吗?或者有没有更简单的方法?

What should I do about this? Should I use exception handling? or is there any easier way?

有什么建议吗?任何帮助都会很棒！

Any suggestions? Any help would be really great!

推荐答案

处理异常才是王道:

try:
    gotdata = dlist[1]
except IndexError:
    gotdata = 'null'

当然你也可以查看dlist的len()；但处理异常更直观.

Of course you could also check the len() of dlist; but handling the exception is more intuitive.

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