列表超出范围12

Question

我想使用BeautifulSoup4来获取BBS的总页数。所以我写了这段代码：

pagenumber = soup.find_all("div",class_="pagelinks")[0]
page_toatal_num = pagenumber.find_all("a")[-1].get_text()
print page_toatal_num

页面的元素在这里：

在这张照片中，我希望得到“342”，按照我的方式，我得到了它。但是，令人困惑的是，它引发了错误：“列表索引超出范围”。在cmd.exe中，它既打印“342”又引发错误。为什么？我怎样才能解决这个问题

Traceback (most recent call last):
  File "C:\Python27\lib\site-packages\scrapy\utils\defer.py", line 102, in iter_
errback
    yield next(it)
  File "C:\Python27\lib\site-packages\scrapy\spidermiddlewares\offsite.py", line
 29, in process_spider_output
    for x in result:
  File "C:\Python27\lib\site-packages\scrapy\spidermiddlewares\referer.py", line
 22, in <genexpr>
    return (_set_referer(r) for r in result or ())
  File "C:\Python27\lib\site-packages\scrapy\spidermiddlewares\urllength.py", li
ne 37, in <genexpr>
    return (r for r in result or () if _filter(r))
  File "C:\Python27\lib\site-packages\scrapy\spidermiddlewares\depth.py", line 5
8, in <genexpr>
    return (r for r in result or () if _filter(r))
  File "C:\python_workspace\deep_web\deep_web\spiders\deepSpider.py", line 73, i
n parse_item
    page_toatal_num = pagenumber.find_all("a")[-1].get_text()
IndexError: list index out of range