Python 有点意思

基本语法

>>> width = 20
>>> height = 2 * 3
>>> width * height
120

>>> x = y = z = 0
>>> x
0
>>> y
0
>>> z
0

变量在使用前，必须定义

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

对浮点数支持很好

>>> 7.0 / 2
3.5
>>> 7 / 2
3

>>> hello = "This is a string
 Hello Python."
>>> print hello
This is a string
 Hello Python.
>>> hello
'This is a string
 Hello Python.'

print 可以输出内容。

字符串可以由 + 操作符连接（粘到一起），可以由 * 重复。

>>> word = 'Help' + 'A'
>>> word
'HelpA'
>>> word * 5
'HelpAHelpAHelpAHelpAHelpA'

这个厉害了。

>>> word[4]
'A'
>>> word[0:2]
'He'
>>> word[2:4]
'lp'
>>> word[:2]
'He'
>>> word[2:]
'lpA'

>>> word[1:100]
'elpA'
>>> word[10:0]
''
>>> word[2:1]
''

>>> word[-1]
'A'
>>> word[-2]
'p'
>>> word[-2:]
'pA'
>>> word[:-2]
'Hel'

 +---+---+---+---+---+
 | H | e | l | p | A |
 +---+---+---+---+---+
 0   1   2   3   4   
-5  -4  -3  -2  -1

>>> s = "hello world"
>>> len(s)
11

>>> u'Hellou0020World !'
u'Hello World !'

转码序列 u0020 表示在指定位置插入编码为 0x0020 的 Unicode 字符（空格）。

>>> h = u'Hellou0020World !'
>>> print h
Hello World !
>>> h
u'Hello World !'

列表

>>> a = ['hello','world',100,20]
>>> a
['hello', 'world', 100, 20]
>>> len(a)
4

>>> a[0]
'hello'
>>> a[3]
20

>>> a[0:2] + ['python',2*2]
['hello', 'world', 'python', 4]

编程

>>> a,b = 0,1
>>> a
0
>>> b
1
>>> while b < 10:
...     print b
...     a,b = b,a+b
... 
1
1
2
3
5
8

>>> i = 2 * 2
>>> print 'The value of i is',i
The value of i is 4

学习给我快乐，没有别的目的。