Python 在过程中返回 None

Question

I have written a program to extract links from a string.

Please check the code below.

def next_target(page):
    if (page.find('<a href') == -1):
        return 0,0
    link = (page.find('<a href='))
    first_quote = (page.find('"', link))
    second_quote = (page.find('"', first_quote + 1))
    url = page[first_quote + 1 : second_quote]
    return url, second_quote

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

print (get_all_links('<div class="no-padding locale-column col-md-3"><a href="https://ee.000webhost.com/" class=""><span class="flag flag-ee"></span><span class="region">Eesti</span> <span class="language">Eesti</span></a><a href="https://es.000webhost.com/" class=""><span class="flag flag-es"></span><span class="region">España</span> <span class="language">Español</span></a><a href="https://fi.000webhost.com/" class=""><span class="flag flag-fi"></span><span class="region">Suomi</span> <span class="language">Suomi</span></a><a href="https://fr.000webhost.com/" class=""><span class="flag flag-fr"></span><span class="region">France</span> <span class="language">Français</span></a><a href="https://gr.000webhost.com/" class=""><span class="flag flag-gr"></span><span class="region">Ελλάδα</span> <span class="language">Ελληνικά</span></a><a href="https://hr.000webhost.com/" class=""><span class="flag flag-hr"></span><span class="region">Hrvatska</span> <span class="language">Hrvatski</span></a><a href="https://hu.000webhost.com/" class=""><span class="flag flag-hu"></span><span class="region">Magyarország</span> <span class="language">Magyar</span></a><a href="https://in.000webhost.com/" class=""><span class="flag flag-en-in"></span><span class="region">India</span> <span class="language">English</span></a><a href="https://th.000webhost.com/" class=""><span class="flag flag-th"></span><span class="region">ประเทศไทย</span> <span class="language">ไทย</span></a></div>'))

The program is extracting all the links. But along with the links, a None value is also returned. How can I stop the None from appearing after the links are extracted?

I have written another program to do the exact same thing. However, it's also returning a None value.

Please check the code below:

def page_pro(page):
    end_quote = 0
    if (page.find('<a href') == -1):
        return None
    else:
        while (page.find('<a href', end_quote) != -1):
            start_link = (page.find('<a href=', end_quote))
            first_quote = (page.find('"', start_link))
            end_quote = (page.find('"', first_quote + 1))
            url = page[first_quote + 1 : end_quote]
            print (url)

print (page_pro('<div class="no-padding locale-column col-md-3"><a href="https://ee.000webhost.com/" class=""><span class="flag flag-ee"></span><span class="region">Eesti</span> <span class="language">Eesti</span></a><a href="https://es.000webhost.com/" class=""><span class="flag flag-es"></span><span class="region">España</span> <span class="language">Español</span></a><a href="https://fi.000webhost.com/" class=""><span class="flag flag-fi"></span><span class="region">Suomi</span> <span class="language">Suomi</span></a><a href="https://fr.000webhost.com/" class=""><span class="flag flag-fr"></span><span class="region">France</span> <span class="language">Français</span></a><a href="https://gr.000webhost.com/" class=""><span class="flag flag-gr"></span><span class="region">Ελλάδα</span> <span class="language">Ελληνικά</span></a><a href="https://hr.000webhost.com/" class=""><span class="flag flag-hr"></span><span class="region">Hrvatska</span> <span class="language">Hrvatski</span></a><a href="https://hu.000webhost.com/" class=""><span class="flag flag-hu"></span><span class="region">Magyarország</span> <span class="language">Magyar</span></a><a href="https://in.000webhost.com/" class=""><span class="flag flag-en-in"></span><span class="region">India</span> <span class="language">English</span></a><a href="https://th.000webhost.com/" class=""><span class="flag flag-th"></span><span class="region">ประเทศไทย</span> <span class="language">ไทย</span></a></div>'))

Answer 1

Here:

print (get_all_links('<div class="no-padding locale-column col-md-3"><a href="https://ee.000webhost.com/" class=""><span class="flag flag-ee"></span><span class="region">Eesti</span> <span class="language">Eesti</span></a><a href="https://es.000webhost.com/" class=""><span class="flag flag-es"></span><span class="region">España</span> <span class="language">Español</span></a><a href="https://fi.000webhost.com/" class=""><span class="flag flag-fi"></span><span class="region">Suomi</span> <span class="language">Suomi</span></a><a href="https://fr.000webhost.com/" class=""><span class="flag flag-fr"></span><span class="region">France</span> <span class="language">Français</span></a><a href="https://gr.000webhost.com/" class=""><span class="flag flag-gr"></span><span class="region">Ελλάδα</span> <span class="language">Ελληνικά</span></a><a href="https://hr.000webhost.com/" class=""><span class="flag flag-hr"></span><span class="region">Hrvatska</span> <span class="language">Hrvatski</span></a><a href="https://hu.000webhost.com/" class=""><span class="flag flag-hu"></span><span class="region">Magyarország</span> <span class="language">Magyar</span></a><a href="https://in.000webhost.com/" class=""><span class="flag flag-en-in"></span><span class="region">India</span> <span class="language">English</span></a><a href="https://th.000webhost.com/" class=""><span class="flag flag-th"></span><span class="region">ประเทศไทย</span> <span class="language">ไทย</span></a></div>'))

or here:

print (page_pro('<div class="no-padding locale-column col-md-3"><a href="https://ee.000webhost.com/" class=""><span class="flag flag-ee"></span><span class="region">Eesti</span> <span class="language">Eesti</span></a><a href="https://es.000webhost.com/" class=""><span class="flag flag-es"></span><span class="region">España</span> <span class="language">Español</span></a><a href="https://fi.000webhost.com/" class=""><span class="flag flag-fi"></span><span class="region">Suomi</span> <span class="language">Suomi</span></a><a href="https://fr.000webhost.com/" class=""><span class="flag flag-fr"></span><span class="region">France</span> <span class="language">Français</span></a><a href="https://gr.000webhost.com/" class=""><span class="flag flag-gr"></span><span class="region">Ελλάδα</span> <span class="language">Ελληνικά</span></a><a href="https://hr.000webhost.com/" class=""><span class="flag flag-hr"></span><span class="region">Hrvatska</span> <span class="language">Hrvatski</span></a><a href="https://hu.000webhost.com/" class=""><span class="flag flag-hu"></span><span class="region">Magyarország</span> <span class="language">Magyar</span></a><a href="https://in.000webhost.com/" class=""><span class="flag flag-en-in"></span><span class="region">India</span> <span class="language">English</span></a><a href="https://th.000webhost.com/" class=""><span class="flag flag-th"></span><span class="region">ประเทศไทย</span> <span class="language">ไทย</span></a></div>'))

you are printing the return value of function, returning nothing. Just omit print(), use

get_all_links(…) 

or

page_pro(…)