第397页 | Learning Python | 阅读 ‧ 电子书库

Test Your Knowledge: Quiz

 

What is the output of the following code, and why?

>>> X = 'Spam'
>>> def func():
...     print(X)
...
>>> func()

What is the output of this code, and why?

>>> X = 'Spam'
>>> def func():
...     X = 'NI!'
...
>>> func()
>>> print(X)

What does this code print, and why?

>>> X = 'Spam'
>>> def func():
...     X = 'NI'
...     print(X)
...
>>> func()
>>> print(X)

What output does this code produce? Why?

>>> X = 'Spam'
>>> def func():
...     global X
...     X = 'NI'
...
>>> func()
>>> print(X)

What about this code—what’s the output, and why?

>>> X = 'Spam'
>>> def func():
...     X = 'NI'
...     def nested():
...         print(X)
...     nested()
...
>>> func()
>>> X

How about this example: what is its output in Python 3.0, and why?

>>> def func():
...     X = 'NI'
...     def nested():
...         nonlocal X
...         X = 'Spam'
...     nested()
...     print(X)
...
>>> func()

Name three or more ways to retain state information in a Python function.