第一周作业（周三）

第2章作业

习题 2-1

mSg = "message"
print(mSg)
print(msg)

结果如下：

message
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'msg' is not defined

我们可以看到第一行输出 message ，第二行却出错了。这说明 Python3 严格区分大小写。

习题 2-2

str = "1234"
print(type(str))
str = 1234
print(type(str))

结果如下：

<class 'str'>
<class 'int'>

我们可以看到两次输出的类型是不同的，说明 Python3 的变量类型是可变的。

习题 2-7

>>> str = "\t\neyufwefuiewfhnwsu fhewuifwheu fhewui cf     "
>>> print(str.lstrip())
eyufwefuiewfhnwsu fhewuifwheu fhewui cf
>>> print(str.rstrip())

eyufwefuiewfhnwsu fhewuifwheu fhewui cf
>>> print(str.strip())
eyufwefuiewfhnwsu fhewuifwheu fhewui cf

2-3 至 2-7 的习题比较简单，就是希望我们了解字符串的用法。

习题 2-11

import this

The Zen of Python, by Tim Peters

Beautiful is better than ugly.
Explicit is better than implicit.
Simple is better than complex.
Complex is better than complicated.
Flat is better than nested.
Sparse is better than dense.
Readability counts.
Special cases aren't special enough to break the rules.
Although practicality beats purity.
Errors should never pass silently.
Unless explicitly silenced.
In the face of ambiguity, refuse the temptation to guess.
There should be one-- and preferably only one --obvious way to do it.
Although that way may not be obvious at first unless you're Dutch.
Now is better than never.
Although never is often better than *right* now.
If the implementation is hard to explain, it's a bad idea.
If the implementation is easy to explain, it may be a good idea.
Namespaces are one honking great idea -- let's do more of those!

哇！python里居然还有这种彩蛋，从来没人告诉过我这个！这些编程理念都是不错的，但不能只是嘴上说说啊……