我认为pat1 =’[ab]’和pat2 =’a |
b’在Python（python2.7，windows）’re’模块中具有与正则表达式模式相同的功能。但是我对’[ab] +’和’（a |
b）+’感到困惑，它们是否具有相同的功能，如果不能，请您详细说明。

'''
Created on 2012-9-4

@author: melo
'''

import re
pat1 = '(a|b)+'
pat2 = '[ab]+'
text = '22ababbbaa33aaa44b55bb66abaa77babab88'

m1 = re.search(pat1, text)
m2 = re.search(pat2, text)
print 'search with pat1:', m1.group()
print 'search with pat2:', m2.group()

m11 = re.split(pat1, text)
m22 = re.split(pat2, text)
print 'split with pat1:', m11
print 'split with pat2:', m22

m111 = re.findall(pat1, text)
m222 = re.findall(pat2, text)
print 'findall with pat1:', m111
print 'findall with pat2:', m222

输出如下：

search with pat1: ababbbaa
search with pat2: ababbbaa
split with pat1: ['22', 'a', '33', 'a', '44', 'b', '55', 'b', '66', 'a', '77', 'b', '88']
split with pat2: ['22', '33', '44', '55', '66', '77', '88']
findall with pat1: ['a', 'a', 'b', 'b', 'a', 'b']
findall with pat2: ['ababbbaa', 'aaa', 'b', 'bb', 'abaa', 'babab']

为什么“ pat1”和“ pat2”不同，它们有什么区别？“ pat1”实际上可以匹配哪种字符串？