再python中,例如下面一段代码是可以实现目标的,输入:
lucky_numbers=[18,99,5,33,88,23,16]
friends=["Kevin","Karen","Jim","Oscar","Tim"]
friends.extend(lucky_numbers)
print(friends)
输出:
C:\Users\Administrator\PycharmProjects\Giraffe\venv\Scripts\python.exe C:/Users/Administrator/PycharmProjects/Giraffe/app.py
['Kevin', 'Karen', 'Jim', 'Oscar', 'Tim', 18, 99, 5, 33, 88, 23, 16]
Process finished with exit code 0
(这是正确的结果)
但是,若代码是这样的:
lucky_numbers=[18,99,5,33,88,23,16]
friends=["Kevin","Karen","Jim","Oscar","Tim"]
print(friends.extend(lucky_numbers))
就会输出结果:
C:\Users\Administrator\PycharmProjects\Giraffe\venv\Scripts\python.exe C:/Users/Administrator/PycharmProjects/Giraffe/app.py
None
Process finished with exit code 0
请问这是什么原理?