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...
You can simply check if the List is empty with:if not my_list: print("List is empty") This is using the Truth Value Testing in Python, also known as implicit booleaness or truthy/falsy value testing.Among other rules it defines that empty sequences and collections like '', (), [],...
defcheck_empty_value(input_list):forelementininput_list:ifelementisNoneorelement=="":returnTruereturnFalsemy_list=[1,2,3,"",5]result=check_empty_value(my_list)print(result)# 输出 True 1. 2. 3. 4. 5. 6. 7. 8. 9. 在上面的代码中,我们定义了一个名为check_empty_value的函数,该函数...
# 判断一个字符串是否为空s=''ifempty(s):print('字符串为空')else:print('字符串不为空')# 判断一个列表是否为空lst=[]ifempty(lst):print('列表为空')else:print('列表不为空')# 判断一个字典是否为空d={}ifempty(d):print('字典为空')else:print('字典不为空') 1. 2. 3. 4. 5. 6...
fruits = [] if fruits: for fruit in fruits: if fruit == 'apples': print('Sorry, we are out of apples right now.') else: print(fruit.title() + ' are available.') else: print('The list is empty.') 输出结果如下图所示。 3.使用多个列表 我们买东西时会自己先列一个清单,然后商店...
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: ... ...
To check if NumPy array is empty in Python, we can use some functions like the size() function will provide the number of elements in the array, any() provides boolean values if any True value is present inside the array, shape() provides the dimension of the array, and tolist() will...
# <project_root>/shared_code/__init__.py # Empty __init__.py file marks shared_code folder as a Python package Python Copy # <project_root>/shared_code/my_second_helper_function.py def double(value: int) -> int: return value * 2 You can start writing test cases for your HT...
The inclusion of the package contents needs to be provided manually; otherwise, the package is mostly empty. You can be more specific if you like, and only include part of it, or exclude part of it, e.g. with --nofollow-import-to='*.tests' you would not include the unused test par...
在Python中没有switch语句。你可以使用if..elif..else语句来完成同样的工作(在某些场合,使用 字典会更加快捷。) 在C/C++中,如果你想要写for (int i = 0; i < 5; i++),那么用Python,你写成for i in range(0,5)。你 会注意到,Python的for循环更加简单、明白、不易出错。