连续两天加班到11点，也是一件挺累的事。忙中偷闲，做了下Python Challenge的第二题，很快就做完了，正好是这几天看了些正则的东西。
第二题的提示很简单：
recognize the characters. maybe they are in the book,
but MAYBE they are in the page source.
ok，是让我们看page source，源码最后面有一段一千多行的字符串，就是像这样的：%%$@_$^__#)^)。
还有一段提示是这样的：find rare characters in the mess below。
先把这段长长的字符串保存到一个txt中，然后解析。源码如下：
import re
f = open('ocr.txt','r')
content = f.read()
print re.findall(r'[a-zA-Z]',content)
运行python ocr.py，结果为：
lyoe@ubuntu:~$ python ocr.py['e', 'q', 'u', 'a', 'l', 'i', 't', 'y']
我们已经得到第三题的地址了：http://www.pythonchallenge.com/pc/def/equality.html
主要是学习re的用法。
Help on function findall in module re:findall(pattern, string, flags=0)Return a list of all non-overlapping matches in the string.If one or more groups are present in the pattern, return alist of groups; this will be a list of tuples if the patternhas more than one group.Empty matches are included in the result.