python的re模块是自带的吗_Python正则re模块使用步骤及原理解析

python中使用正则表达式的步骤&＃xff1a;

1.导入re模块&＃xff1a;import re

2.初始化一个Regex对象&＃xff1a;re.compile()

3.刚刚创建的Regex对象调用search方法进行匹配&＃xff0c;返回要给March对象

4.刚刚的March对象调用group方法&＃xff0c;展示匹配到的字符串

下面例子的知识点&＃xff1a;

对正则表达式分组用&＃xff1a;()&＃xff0c;正则里的分组计数从1开始&＃xff0c;不是从0&＃xff0c;切记~~

group(数字)&＃xff1a;去对应的分组的值

groups():返回所有分组的元组形式

\d表示一个数字

regex_obj &＃61; re.compile(r&＃39;(\d\d\d)-(\d\d\d)-(\d\d\d\d)&＃39;)

match_obj &＃61; regex_obj.search(&＃39;我司电话&＃xff1a;035-411-1234&＃39;)

result1 &＃61; match_obj.group(1)

result2 &＃61; match_obj.group(2)

result3 &＃61; match_obj.group(3)

print(result1)

print(result2)

print(result3)

result4 &＃61; match_obj.group()

print(result4)

result5 &＃61; match_obj.groups()

print(result5)

执行结果&＃xff1a;

035

411

1234

035-411-1234

(&＃39;035&＃39;, &＃39;411&＃39;, &＃39;1234&＃39;)

补充知识点&＃xff1a;\w表示一个单词&＃xff0c;\s表示一个空格

regex_obj &＃61; re.compile(r&＃39;(\d\w\d)-(\d\d\d)-(\d\d\d\d)&＃39;)

match_obj &＃61; regex_obj.search(&＃39;我司电话&＃xff1a;0a5-411-1234&＃39;)

result &＃61; match_obj.group(1)

print(result)

regex_obj &＃61; re.compile(r&＃39;(\d\w\d)-(\d\d\d)-(\d\d\d\d)&＃39;)

match_obj &＃61; regex_obj.search(&＃39;我司电话&＃xff1a;0哈5-411-1234&＃39;)

result &＃61; match_obj.group(1)

print(result)

regex_obj &＃61; re.compile(r&＃39;(\d\s\d)-(\d\d\d)-(\d\d\d\d)&＃39;)

match_obj &＃61; regex_obj.search(&＃39;我司电话&＃xff1a;0 5-411-1234&＃39;)

result &＃61; match_obj.group(1)

print(result)

执行结果&＃xff1a;

0a5

0哈5

0 5

| 或&＃xff1a;

regex_obj &＃61; re.compile(r&＃39;200|ok|successfully&＃39;)

match_obj1 &＃61; regex_obj.search(&＃39;vom get request and stored successfully&＃39;)

result1 &＃61; match_obj1.group()

print(result1)

match_obj2 &＃61; regex_obj.search(&＃39;vom get request,response 200 ok&＃39;)

result2 &＃61; match_obj2.group()

print(result2)

match_obj3 &＃61; regex_obj.search(&＃39;vom get request,response ok 200&＃39;)

result3 &＃61; match_obj3.group()

print(result3)

执行结果&＃xff1a;

successfully

200

ok

注意&＃xff1a;如果search返回的March对象只有一个结果值的话&＃xff0c;不能用groups&＃xff0c;只能用group

regex_obj &＃61; re.compile(r&＃39;200|ok|successfully&＃39;)

match_obj1 &＃61; regex_obj.search(&＃39;vom get request and stored successfully&＃39;)

result2 &＃61; match_obj1.groups()

print(result2)

result1 &＃61; match_obj1.group()

print(result1)

执行结果&＃xff1a;

()

successfully

? &＃xff1a;可选匹配项

&＃43; &＃xff1a;1次 或 n次 匹配

* &＃xff1a;*前面的字符或者字符串匹配 0次、n次

注意&＃xff1a;*前面必须要有内容

regex_obj &＃61; re.compile(r&＃39;(haha)*,welcome to vom_admin system&＃39;) 指haha这个字符串匹配0次或者多次

regex_obj &＃61; re.compile(r&＃39;(ha*),welcome to vom_admin system&＃39;) 指ha这个字符串匹配0次或者多次

. : 通配符&＃xff0c;匹配任意一个字符

所以常常用的组合是&＃xff1a;.*

regex_obj &＃61; re.compile(r&＃39;(.*),welcome to vom_admin system&＃39;)

match_obj1 &＃61; regex_obj.search(&＃39;Peter,welcome to vom_admin system&＃39;)

name &＃61; match_obj1.group(1)

print(name)

执行结果&＃xff1a;

Peter

{} &＃xff1a; 匹配特定的次数

里面只写一个数字&＃xff1a;匹配等于数字的次数

里面写{3,5}这样两个数字的&＃xff0c;匹配3次 或 4次 或 5次&＃xff0c;按贪心匹配法&＃xff0c;能满足5次的就输出5次的&＃xff0c;没有5次就4次&＃xff0c;4次也没有才是3次

regex_obj &＃61; re.compile(r&＃39;((ha){3}),this is very funny&＃39;)

match_obj1 &＃61; regex_obj.search(&＃39;hahahaha,this is very funny&＃39;)

print("{3}结果",match_obj1.group(1))

regex_obj &＃61; re.compile(r&＃39;((ha){3,5}),this is very funny&＃39;)

match_obj1 &＃61; regex_obj.search(&＃39;hahahaha,this is very funny&＃39;)

print("{3,5}结果",match_obj1.group(1))

执行结果&＃xff1a;

{3}结果 hahaha

{3,5}结果 hahahaha

findall()&＃xff1a;返回所有匹配到的字串的列表

regex_obj &＃61; re.compile(r&＃39;\d\d\d&＃39;)

match_obj &＃61; regex_obj.findall(&＃39;我是101班的&＃xff0c;小李是103班的&＃39;)

print(match_obj)

regex_obj &＃61; re.compile(r&＃39;(\d\d\d)-(\d\d\d)-(\d\d\d\d)&＃39;)

match_obj &＃61; regex_obj.findall(&＃39;我家电话是123-123-1234&＃xff0c;我公司电话是890-890-7890&＃39;)

print(match_obj)

打印结果&＃xff1a;

[&＃39;101&＃39;, &＃39;103&＃39;]

[(&＃39;123&＃39;, &＃39;123&＃39;, &＃39;1234&＃39;), (&＃39;890&＃39;, &＃39;890&＃39;, &＃39;7890&＃39;)]

[]&＃xff1a;创建自己的字符集&＃xff1a;

[abc]&＃xff1a;包括[]内的字符

[^abc]&＃xff1a;不包括[]内的所有字符

也可以使用:[a-zA-Z0-9]这样简写

regex_obj &＃61; re.compile(r&＃39;[!&＃64;#$%^&*()]&＃39;)

name &＃61; input("请输入昵称&＃xff0c;不含特殊字符&＃xff1a;")

match_obj &＃61; regex_obj.search(name)

if match_obj:

print("昵称输入不合法&＃xff0c;包含了特殊字符&＃xff1a;", match_obj.group())

else:

print("昵称有效")

执行结果&＃xff1a;

请输入昵称&＃xff0c;不含特殊字符&＃xff1a;*h

昵称输入不合法&＃xff0c;包含了特殊字符&＃xff1a; *

^&＃xff1a;开头

$&＃xff1a;结尾

regex_obj &＃61; re.compile(r&＃39;(^[A-Z])(.*)&＃39;)

name &＃61; input("请输入昵称&＃xff0c;开头必须大写字母&＃xff1a;")

match_obj &＃61; regex_obj.search(name)

print(match_obj.group())

执行结果&＃xff1a;

请输入昵称&＃xff0c;开头必须大写字母&＃xff1a;A1234

A1234

sub()&＃xff1a;第一个参数为要替换成的&＃xff0c;第二个参数传被替换的&＃xff0c;返回替换成功后的字符串

regex_obj &＃61; re.compile(r&＃39;[!&＃64;#$%^&*()]&＃39;)

match_obj &＃61; regex_obj.sub(&＃39;嘿&＃39;,&＃39;haha,$%^,hahah&＃39;)

print(match_obj)

执行结果&＃xff1a;

haha,嘿嘿嘿,hahah

补充一下正则表达式的表&＃xff0c;正则太复杂了&＃xff0c;要常看常用才能熟练

以上就是本文的全部内容&＃xff0c;希望对大家的学习有所帮助&＃xff0c;也希望大家多多支持。