demo3.py

#!/usr/bin/python3
# 正则表达式

import re

print(re.match('www', 'www.w3cschool.cn').span())  # 在起始位置匹配
print(re.match('cn', 'www.w3cschool.cn'))  # 不在起始位置匹配

line = "Cats are smarter than dogs";

searchObj = re.search(r'(.*) are (.*?) .*', line, re.M | re.I)

if searchObj:
    print("searchObj.group() : ", searchObj.group())
    print("searchObj.group(1) : ", searchObj.group(1))
    print("searchObj.group(2) : ", searchObj.group(2))
else:
    print("Nothing found!!")

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!!")