第二种方法是使用is关键字来判断一个值是否为None。None是Python中表示空值的特殊对象。我们可以使用is关键字来判断一个值是否等于None。下面是示例代码: defcheck_input(username,password):ifusernameisNone:print("用户名不能为空")ifpasswordisNone:print("密码不能为空")username=input("请输入用户名:")passwo...
ifnotvariable:print("变量为空")else:print("变量不为空") 1. 2. 3. 4. 其中,variable是需要判断的变量。 代码示例 下面是一个完整的示例代码,展示了如何使用条件判断语句和特定的方法来判断变量是否为空: # 步骤二示例代码:使用条件判断语句判断变量是否为空defcheck_variable_with_if(variable):ifvariable:...
# unit test caseimportunittestclassTestMethods(unittest.TestCase):# test functiondeftest_positive(self):firstValue ="geeks"# error message in case if test case got failedmessage ="Test value is none."#assertIsNotNone() to check that if input value is not noneself.assertIsNotNone(firstValue...
defcheck_full_rows(grid,grid_height,grid_width):full_rows=[]foryinrange(grid_height):ifall(gri...
None类型的应用场景 None作为一个特殊的字面量,用于表示:空,没有意义,有很多实际的应用场景。 用在函数无返回值上 用在if判断上 在if判断中None等于False 一般用于函数主动返回None,配合if做相关判断。 def check_age(age): if age>18: return "success" return None r=check_age(5) if not r: print("...
1#使用__metaclass__(元类)的高级python用法2classSingleton2(type):3def__init__(cls,name,bases,dict):4super(Singleton2,cls).__init__(name,bases,dict)5cls._instance=None6def__call__(cls,*args,**kw):7ifcls._instance is None:8cls._instance=super(Singleton2,cls).__call__(*args,*...
The equality operator == is another way to check if variable is None in Python, but it is not recommended. Using the is keyword 1 2 3 4 5 x = None if(x == None): print("x is of the 'None' type.") Output: x is of the ‘None’ type. The == operator checks whether ...
check() page.get_by_role("button", name=re.compile("submit", re.IGNORECASE)).click() 参数:太多了,看源码吧,其中role参数比较重要,比如alert就可以用来点击弹窗。 role:必填项,可选如下 "alert"|"alertdialog"|"application"|"article"|"banner"|"blockquote"|"button"|"caption"|"cell"|"checkbox"...
print("is None")iffoo ==None: print("also none") Using 'is' can be better when check is None or not, because 'is' is doing id comparsion: id(foo) == id(None) It is much faster check '==' it does a deep looking for the value....
x="abc"ifx==None:print("Value of x is None")else:print("x is not None") However, most people would recommend you to useisinstead of==because theiskeyword is faster than the equality operator. Theiskeyword doesn’t check for the value of the operands. It simply sees if the two opera...