[regular expression] single character matching

1. Match a single character

adopt re The module can complete the use of regular expressions to match strings

Code	function
.	Match arbitrarily 1 Characters （ except \n）
[ ]	matching [ ] The characters listed in
\d	Match the Numbers , namely 0-9
\D	Match non numeric , It's not numbers
\s	Match blanks , namely Space ,tab key
\S	Match non blank
\w	Match non special characters , namely a-z、A-Z、0-9、_、 Chinese characters
\W	Match special character , It's not a letter 、 The digital 、 Non Chinese characters

Example 1： .

import re

ret = re.match(".","M")
print(ret.group())

ret = re.match("t.o","too")
print(ret.group())

ret = re.match("t.o","two")
print(ret.group())

Running results ：

M
too
two

Example 2：[]

import re

#  If hello The first character of is lowercase , So regular expressions need lowercase h
ret = re.match("h","hello Python") 
print(ret.group())


#  If hello The first character of is capitalized , So regular expressions need to be capitalized H
ret = re.match("H","Hello Python") 
print(ret.group())

#  Case write h All right 
ret = re.match("[hH]","hello Python")
print(ret.group())
ret = re.match("[hH]","Hello Python")
print(ret.group())
ret = re.match("[hH]ello Python","Hello Python")
print(ret.group())

#  matching 0 To 9 The first way to write it 
ret = re.match("[0123456789]Hello Python","7Hello Python")
print(ret.group())

#  matching 0 To 9 The second way 
ret = re.match("[0-9]Hello Python","7Hello Python")
print(ret.group())

ret = re.match("[0-35-9]Hello Python","7Hello Python")
print(ret.group())

#  The following rule can't match numbers 4, therefore ret by None
ret = re.match("[0-35-9]Hello Python","4Hello Python")
# print(ret.group())

Running results ：

h
H
h
H
Hello Python
7Hello Python
7Hello Python
7Hello Python

Example 3：\d

import re

#  A normal match 
ret = re.match(" The goddess of the moon 1 Number "," The goddess of the moon 1 The launch was successful ") 
print(ret.group())

ret = re.match(" The goddess of the moon 2 Number "," The goddess of the moon 2 The launch was successful ") 
print(ret.group())

ret = re.match(" The goddess of the moon 3 Number "," The goddess of the moon 3 The launch was successful ") 
print(ret.group())

#  Use \d Match 
ret = re.match(" The goddess of the moon \d Number "," The goddess of the moon 1 The launch was successful ") 
print(ret.group())

ret = re.match(" The goddess of the moon \d Number "," The goddess of the moon 2 The launch was successful ") 
print(ret.group())

ret = re.match(" The goddess of the moon \d Number "," The goddess of the moon 3 The launch was successful ") 
print(ret.group())

Running results ：

 The goddess of the moon 1 Number 
 The goddess of the moon 2 Number 
 The goddess of the moon 3 Number 
 The goddess of the moon 1 Number 
 The goddess of the moon 2 Number 
 The goddess of the moon 3 Number 

Example 4：\D

import re

match_obj = re.match("\D", "f")
if match_obj:
    #  Get matching results 
    print(match_obj.group())
else:
    print(" Matching failure ")

Running results :

f

Example 5：\s

import re

#  Spaces are white space characters 
match_obj = re.match("hello\sworld", "hello world")
if match_obj:
    result = match_obj.group()
    print(result)
else:
    print(" Matching failure ")



# \t  It's a white space character 
match_obj = re.match("hello\sworld", "hello\tworld")
if match_obj:
    result = match_obj.group()
    print(result)
else:
    print(" Matching failure ")

Running results :

hello world
hello world

Example 6：\S

import re

match_obj = re.match("hello\Sworld", "hello&world")
if match_obj:
result = match_obj.group()
print(result)
else:
print(" Matching failure ")



match_obj = re.match("hello\Sworld", "hello$world")
if match_obj:
result = match_obj.group()
print(result)
else:
print(" Matching failure ")

Running results :

hello&world  
hello$world

Example 7：\w

import re

#  Match one of the non special characters 
match_obj = re.match("\w", "A")
if match_obj:
    #  Get matching results 
    print(match_obj.group())
else:
    print(" Matching failure ")

Execution results :

A

Example 8：\W

#  Match one of the special characters 
match_obj = re.match("\W", "&")
if match_obj:
    #  Get matching results 
    print(match_obj.group())
else:
    print(" Matching failure ")

Execution results :

&