You can simply check if the List is empty with: ifnotmy_list:print("List is empty") This is using theTruth Value Testingin Python, also known as implicit booleaness or truthy/falsy value testing. Among other rules it defines that empty sequences and collections like'', (), [], {},...
A more explicit way to check if a list is empty is to use Python's built-inlen()function, which returns the number of items in a list. Here's how you can uselen()to check if a list is empty: my_list=[]iflen(my_list)==0:print("The list is empty")else:print("The list is...
a = []iflen(a) ==0:print("empty list") 写法二 Copy a = []ifnota:print("empty list") 这两种写法都很常见。那么问题来了,第一种写法用列表长度去判断列表为空可以理解,那么第二种写法直接去判断,这是怎么判断出来的呢? if 为了解决这个问题,我们首先需要重新认识一下if。关于 if 是用来做条件执...
我们使用条件语句来判断列表是否为空。如果列表为空(即列表的布尔值为 False),则输出 “The list is empty”;如果列表不为空(列表的布尔值为 True),则输出 “The list is not empty”。 代码语言:javascript 代码运行次数:0 运行 AI代码解释 ifnot my_list:print("The list is empty")else:print("The li...
if sys.version_info >= (3,): def __imul__(self: _S, n: int) -> _S: ... def __contains__(self, o: object) -> bool: ... def __reversed__(self) -> Iterator[_T]: ... def __gt__(self, x: List[_T]) -> bool: ... ...
当数据不应该被复制时,例如因为数据太大或者函数设计需要在原地更改数据以使调用者受益时,调用list()会很糟糕。在这种情况下,像isinstance(x, abc.MutableSequence)这样的运行时检查将是一个好方法。如果你担心得到一个无限生成器——这不是一个常见问题——你可以先调用len()来检查参数。这将拒绝迭代器,同时安全...
numbers = [2, 4, 6, 8, 1] for number in numbers: if number % 2 == 1: print(number) break else: print("No odd numbers") 如果找到了奇数,就会打印该数值,并且执行break语句,跳过else语句。没有的话,就不会执行break语句,而是执行else语句。 ▍2、从列表中获取元素,定义多个变量 my_list = ...
y = map(lambda i: i ** 2, list) decorator装饰器 装饰器是把一个要执行的函数包含在wrapper函数里面,并且在要执行的函数前后去执行代码 classmethod和staticmethod staticmethod不需要已经实例化的类的函数来作为输入,可以传入任何东西。method中不使用self就不会改变class instance,因此不传入class instance或者没有...
Common Mistake #10: Misusing the__del__method Let’s say you had this in a file calledmod.py: import fooclassBar(object): ...def__del__(self): foo.cleanup(self.myhandle) And you then tried to do this fromanother_mod.py:
del_recycle_bin() devices_res_space = get_residual_space(all_devices_paths) ret = check_devices_space(devices_res_space, need_space) if ret == OK: print_ztp_log("Empty recycle bin, the space enough and continue ztp...", LOG_INFO_TYPE) return OK devices_files_list = get_mpus_...