【自学python】 关于爬虫int问题出错

Question

代码如下：

from urllib.request import urlopen
from bs4 import BeautifulSoup

html = urlopen("http://ent.sina.com.cn")


page = BeautifulSoup(html)



def get_next_target(page):
    start_link = page.find('<a href=')
    if start_link == -1:
        url, end_quote = None, 0
        return url, end_quote

    else:
        start_quote = page.find('"', start_link)
        end_quote = page.find('"', start_quote + 1)
        url = page[start_quote + 1:end_quote]

    return url, end_quote



def print_all_links(page):
    while True:
        url, endpos = get_next_target(page)
        if url:
            print( url)
            page = page[endpos:]
        else:
            break

print_all_links(get_next_target(page))

执行结果如下：

复制下来就是：

python@ubuntu:~$ python3 aa.py 
/usr/lib/python3/dist-packages/bs4/__init__.py:166: UserWarning: No parser was explicitly specified, so I'm using the best available HTML parser for this system ("lxml"). This usually isn't a problem, but if you run this code on another system, or in a different virtual environment, it may use a different parser and behave differently.

To get rid of this warning, change this:

 BeautifulSoup([your markup])

to this:

 BeautifulSoup([your markup], "lxml")

  markup_type=markup_type))
Traceback (most recent call last):
  File "aa.py", line 35, in <module>
    print_all_links(get_next_target(page))
  File "aa.py", line 19, in get_next_target
    end_quote = page.find('"', start_quote + 1)
TypeError: unsupported operand type(s) for +: 'NoneType' and 'int'

这个是我自制的一个爬虫函数，然后出错了。这个到底错在哪里呢？看不懂

Answer 1

https://www.crummy.com/softwa...

find 的第一个参数必须是标签名，你传一个引号当然找不到

Answer 2

这里的错误是
start_quote为None
start_quote + 1 肯定加不起