res=requests.get("https://www.zhipin.com/gongsi/_zzz_c101010100_iy100014_t801_s301/",headers=headers)
turn=etree.HTML(res.text).xpath("//div[@class="page"]/a[contains(@ka,"page-next")]/@href")
turn
[]
next_page is not None
Traceback (most recent call last):
File "<input>", line 1, in <module>
NameError: name "next_page" is not defined
turn is not None
True
turn
[]
if turn:
print("sss")
turn is not None
True
turn is None
False
is not None is not None
because the xpath you wrote does not match the data, you are returned an empty list, not None' is not None'! = None
= tests value where is tests to see if they are the same object
because [] is an empty list, it is not None ah. If the condition of
if is 0 , empty string ', empty list [] , Boolean value False , None , it will be judged as False , and the conditional statement will not be executed.
xx is not None = xx! = None
if xx = if xx! = None and xx =''and xx! = False and xx! = 0 and xx! = [] and xx! = {} and.
the subject needs to know the difference between falsy and False , () [] None code these are all code , but not all of them. python-how-is-it-different-from-true-and-false" rel=" nofollow noreferrer "> What is Truthy and Falsy in python? How is it different from True and False?
None is a special object, and the Boolean value of an object is determined by _ _ bool__ and _ _ len__ special methods. None is more often used as a sentinel object, such as determining whether a loop is executed.
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