[regular expression] match the beginning and end

1. Match the beginning and the end

Code	function
^	Match the beginning of a string
$	Match string end

Example 1：^

demand ： Match data that starts with a number

import re

#  Match data that starts with a number 
match_obj = re.match("^\d.*", "3hello")
if match_obj:
    #  Get matching results 
    print(match_obj.group())
else:
    print(" Matching failure ")

Running results :

3hello

Example 2：$

demand : Match data ending in numbers

import re
#  Match data ending in numbers 
match_obj = re.match(".*\d$", "hello5")
if match_obj:
    #  Get matching results 
    print(match_obj.group())
else:
    print(" Matching failure ")

Running results ：

hello5

Example 3：^ and $

demand : Match the middle content starting with a number, regardless of ending with a number

match_obj = re.match("^\d.*\d$", "4hello4")
if match_obj:
    #  Get matching results 
    print(match_obj.group())
else:
    print(" Matching failure ")

Running results :

4hello4

2. Matches all but the specified characters

[^ Specify the characters ]: Indicates that all characters except the specified ones match

demand : The first character except aeiou All characters match

import re


match_obj = re.match("[^aeiou]", "h")
if match_obj:
    #  Get matching results 
    print(match_obj.group())
else:
    print(" Matching failure ")

Execution results

h