Regular expressions: examples (1)

1、 user name

The user name can contain the following characters ：
1、26 Upper and lower case English letters are expressed as a-zA-Z.
2、 The number is expressed as 0-9.
3、 The underline is indicated by _.
4、 A dash in the middle indicates -.

The user name consists of several letters 、 Numbers 、 Underline and underline form , So you need to use + Express 1 Appear several times or more . According to the above conditions, the expression of user name can be ：

[a-zA-Z0-9-_]+

>>> import re
>>> pattern = r"[a-zA-Z0-9_-]+"
>>> text = "lily123"
>>> match = re.search(pattern, text)
>>> match
<re.Match object; span=(0, 7), match='lily123'>

2、HTML label

matching html Medium <p> label ：

<p((\s\S)*)<\/p>

>>> import re
>>> text = '''<p class="odd" id="odd">123</p>'''
>>> pattern = r"<p(([\s\S])*)<\/p>"
>>> re.search(pattern, text)
<re.Match object; span=(0, 31), match='<p class="odd" id="odd">123</p>'>

3、 cell-phone number

The first digit of the mobile phone number is 1, The second digit cannot be 0、1、2, Altogether 11 position . The regular expression obtained from the above conditions is ：

^1[^012]\d{9}$

>>> import re
>>> pattern = r"^1[^012]\d{9}$"
>>> phone_number = "13174335288"
>>> match = re.search(pattern, phone_number)
>>> match
<re.Match object; span=(0, 11), match='13174335288'>