Python正则表达式中flags参数的实例详解

import re
text = '我爱Python我爱python'
pat1 = 'p'
# search
r1 = re.findall(pattern=pat1, string=text, flags=re.I)
print(r1)

import re
text = '我爱数学\n我爱Python\n我爱python'
pat1 = '^我'
# search
r1 = re.findall(pattern=pat1, string=text)
r2 = re.findall(pattern=pat1, string=text, flags=re.M)
print(r1)
print(r2)

import re
text = '''
我爱Python
我爱pandas
'''
pat1 = '.我'
# search
r1 = re.findall(pattern=pat1, string=text, flags=re.S)
print(r1)
r2 = re.findall(pattern=pat1, string=text)
print(r2)

In [63]: s
Out[63]: 'first line\nsecond line\nthird line'
 
In [64]: pattern=re.compile(r'^\w+')
 
In [65]: re.findall(pattern,s)
Out[65]: ['first']
 
In [67]: pattern=re.compile(r'^\w+',re.M)
 
In [68]: re.findall(pattern,s)
Out[68]: ['first', 'second', 'third']

In [62]: s = '''first line
    ...: second line
    ...: third line'''
 
In [71]: regex=re.compile('.+',re.S)
 
In [73]: regex.findall(s)
Out[73]: ['first line\nsecond line\nthird line']
 
In [74]: regex=re.compile('.+')
 
In [75]: regex.findall(s)
Out[75]: ['first line', 'second line', 'third line']

email_regex = re.compile("[\w+\.]+@[a-zA-Z\d]+\.(com|cn)")
 
email_regex = re.compile("""[\w+\.]+  # 匹配@符前的部分
                            @  # @符
                            [a-zA-Z\d]+  # 邮箱类别
                            \.(com|cn)   # 邮箱后缀  """, re.X)