参考这里：
| Match Object Methods | Description |
|---|---|
| group(num=0) | This methods returns entire match (or specific subgroup num) |
| groups() | This method return all matching subgroups in a tuple (empty if there weren’t any) |
知道了，原来group(0)，是所有匹配的内容，而group(N)指的是原先subgroup子组对应的内容，而subgroup是原先search等规则中，用括号()所括起来的。
举例1：
#!/usr/bin/python
import re
line = "Cats are smarter than dogs";
matchObj = re.search( r'(.*) are(\.*)', line, re.M|re.I)
if matchObj:
print "matchObj.group() : ", matchObj.group()
print "matchObj.group(1) : ", matchObj.group(1)
print "matchObj.group(2) : ", matchObj.group(2)
else:
print "No match!!"
输出是：
matchObj.group(): Cats are
matchObj.group(1) : Cats
matchObj.group(2) :
举例2：字符串：
var pre = [false,'', '','\/recommend_music/blog/item/.html'];
然后去search：
match = re.search(r"var pre = \[(.*?),.*?,.*?,'(.*?)'\]", page, re.DOTALL | re.IGNORECASE | re.MULTILINE)print "match(0)=", match.group(0),"match(1)=",match.group(1),"match(2)=",match.group(2),"match(3)=",match.group(3)
得到的输出是：
match(0)= var pre = [false,'', '','\/recommend_music/blog/item/.html']
match(1)= false
match(2)= \/recommend_music/blog/item/.html
match(3)=
 |  |  |
| 6.1. re模块搜索时要注意竖线"|"的使用 |  | 6.3. re模块的findall的模式（pattern）中是否加括号的区别 |
