python字符对象方法

1. str.split()，str.join(list)

In [10]: ip="192.168.1.123"

In [11]: ip.split(".")
Out[11]: ['192', '168', '1', '123']

In [12]: ip.split(".")[-1]
Out[12]: '123'
In [13]: ip_=ip.split(".")

In [14]: ip_
Out[14]: ['192', '168', '1', '123']

In [15]: "-".join(ip_)
Out[15]: '192-168-1-123'
In [16]: type(ip_)
Out[16]: list

2.str.find()，len(str)，str.index(sub[, start[, end]])

find找不到返回-1,index找不到会抛出错误

In [18]: a='abcdefg'

In [19]: a.find('c')
Out[19]: 2
In [26]: len(a)
Out[26]: 7

In [26]: len(a)
Out[26]: 7

In [47]: s
Out[47]: 'abcdefgaabcdefaac'

In [48]: s.index('a')
Out[48]: 0

In [49]: s.index('a',1)
Out[49]: 7

In [50]: s.index('k',1)
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-50-ae6ca9f6a7c4> in <module>()
----> 1 s.index('k',1)

ValueError: substring not found

In [57]: s.find("k")
Out[57]: -1

3. str.center(width,[,fillchar])
以str居中用fillchar填充凑够width

In [34]: a.center(5,'-')
Out[34]: '-php-'

In [35]: a.center(10,'-')
Out[35]: '---php----'

In [36]: a.center(10,'|')
Out[36]: '|||php||||'

4.str.count(sub[, start[, end]])

In [42]: s
Out[42]: 'abcdefgaabcdefaac

In [43]: s.count('a')
Out[43]: 5

In [44]: s.count('a',1)
Out[44]: 4

In [45]: s.count('a',1,7)
Out[45]: 0

In [46]: s.count('a',1,8)
Out[46]: 1

help(str)
help(str.index)