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:")password=input("请输入密码:")check_input(username,passw...
print(f"无返回值函数,返回的内容类型是:{type(result)}") # None用于if判断 def check_age(age): if age > 18: return "SUCCESS" else: return None result = check_age(16) if not result: # 进入if表示result是None值 也就是False print("未成年,不可以进入") # None用于声明无初始内容的变量 n...
In Python, Check if Variable Is None and Check if Variable Is null have same solutions as meaning of both queries is same.
1.您不必在循环体内部测试这些列表引用中是否有一个是None，因为可以确保None也不是。1.在循环之后，你...
3. Check String is Empty Using not OperatorThe not operator is a logical operator that returns True if the value or expression is False, and False if the value or expression is True. So if we specify not before the string in the if condition, It will become True when the string is ...
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....
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("...
假设一个方块落地的逻辑已经实现if方块落地:# 将方块固定到网格上# ...# 检查是否有行被填满full_...
Typehelp()forinteractive help,orhelp(object)forhelp about object.>>>help()Welcome to Python3.6's help utility!Ifthisis your first time using Python,you should definitely check out the tutorial on the Internet at https://docs.python.org/3.6/tutorial/.Enter the nameofany module,keyword,or top...
unittestclassTestMethods(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, message)if__name__...