简而言之是re.match只匹配字符串的开始，如果字符串开始不符合正则表达式，则匹配失败，函数返回None；

而re.search匹配整个字符串，直到找到一个匹配



# ————————代码示范————————————
#!/usr/bin/python

import re

line = "Cats are smarter than dogs";

matchObj = re.match( r'dogs', line, re.M|re.I)

if matchObj:  

   print "match --> matchObj.group() : ", matchObj.group()

else:   print "No match!!"

matchObj = re.search( r'dogs', line, re.M|re.I)

    if matchObj:

      print "search --> matchObj.group() : ", matchObj.group()

    else:   

       print "No match!!"

# ——————————输出结果↓————————————
No match!!

search --> matchObj.group() :  dogs