re.match()的使用
尝试从字符串的起始位置匹配一个模式，如果不是起始位置匹配成功的话，match（）就返回None
1.最常规的匹配
import re contect = 'Hello 123 456789 World_this is a Regex Demo'res= re.match('^Hello\s\d\d\d\s\d{6}\s\w{10}.*Demo$', contect)print(res)
print(res.group()) #获取匹配内容
print(res.span()) #查看匹配长度
print(len(contect)) #len统计字符串的数量
<re.Match object; span=(0, 43), match='Hello 123 456789 World_this is a Regex Demo'>
Hello 123 456789 World_this is a Regex Demo
(0, 43)
43
a_str = 'qwe 123 ghj'
res = re.match('^q\w{2}\s\d{3}.*j$', a_str)
print(res.group())
qwe 123 ghj
2.范匹配
contect = 'Hello 123 4567 World_This is a Regex'result = re.match('^H.*?Regex$', contect)
print(result.group())
print(result.span())
Hello 123 4567 World_This is a Regex
(0, 36)
3.匹配目标–分组匹配(可用()进行分组匹配)
contect = 'qwe Hello 1234567 world_This is a Regex Demo'# result = re.match('^qwe\s(\w+)\s(\d{7}).*Demo$', contect) #括号分组
result = re.match('^qwe\s(\w+)\s(\d{3}).*Demo$', contect) #第二组匹配前3个数
print(result.group())
print(result.group(1))
print(result.group(2))
qwe Hello 1234567 world_This is a Regex Demo
Hello
123
sssd = 'dasdjskL22222adjlsakjddd666666dasssssssa'result = re.match('^d.*L(\d+).*ddd(\d+)d.*a$', sssd)
print(result)
print(result.group(1))
print(result.group(2))
<re.Match object; span=(0, 40), match='dasdjskL22222adjlsakjddd666666dasssssssa'>
22222
666666
4.贪婪匹配(尽可能多的去匹配)
content = 'Hello 1234567 world_This is a Regex Demo'result = re.match('^He.*(\d+)\s.*Demo$', content)
print(result)
print(result.group(1))
<re.Match object; span=(0, 40), match='Hello 1234567 world_This is a Regex Demo'>
7
5.非贪婪模式(尽可能少的去匹配)
content = 'Hello 1234567 world_This is a Regex Demo'result = re.match('^He.*?(\d+).*Demo$', content)
print(result)
print(result.group(1))
<re.Match object; span=(0, 40), match='Hello 1234567 world_This is a Regex Demo'>
1234567
6.匹配模式(针对换行) re.S
#re.S匹配包括换行在内的所有字符
content = '''Hello 1234567 world_This
is a Regex Demo
'''
result = re.match('^He.*?(\d+).*Demo$', content, re.S)
print(result)
print(result.group(1))
<re.Match object; span=(0, 40), match='Hello 1234567 world_This\nis a Regex Demo'>
1234567
7.转义
#错误
content = 'price is $5.00' # .是正则里的特殊匹配符号result = re.match('price is $5.00', content)
print(result)
None
#正确
content = 'price is $5.00' # .是正则里的特殊匹配符号result = re.match('price is \$5\.00', content)
print(result)
print(result.group())
<re.Match object; span=(0, 14), match='price is $5.00'>
price is $5.00
尽量使用非贪婪模式
re.search()方法的使用
re.search()扫描整个字符串并返回第一个成功的匹配
content = 'Extra stings Hello 1234567 World_This is a Regex Demo Extra stings'# result = re.match('He.*?(\d+).*?Wor', content) #None
result = re.match('Ex.*?(\d+).*?Wor', content)
print(result)
<re.Match object; span=(0, 30), match='Extra stings Hello 1234567 Wor'>
content = 'Extra stings Hello 1234567 World_This is a Regex Demo Extra stings'result = re.search('He.*?(\d+).*?Wor', content)
print(result)
print(result.group(1))
<re.Match object; span=(13, 30), match='Hello 1234567 Wor'>
1234567
html = '''<li data-view="4" class="active"><a href="/3.mp3" singer="老秦">往事随风</a></li>
'''result = re.search('<li.*?class="active".*?singer="(.*?)">(.*?)</a>.*?</li>', html, re.S)
print(result.group(1))
print(result.group(2))
老秦
往事随风
re.findall()
拿到所有满足要求的数据
找到数据的共同点,基本不一样的地方用.*?
re.sub()
替换字符串中每一个匹配的字符串后返回替换后的字符串
content = 'Extra stings Hello 1234567 World_This is a Regex Demo Extra stings'
#第一个参数 正则表达式
#第二个参数 要替换的字符串
#第三个参数 原字符串
content = re.sub('s', '7', content)
print(content)
Extra 7ting7 Hello 1234567 World_Thi7 i7 a Regex Demo Extra 7ting7
content = 'Extra stings Hello 1234567 World_This is a Regex Demo Extra stings'content = re.sub('\d+', '66666666', content)
print(content)
Extra stings Hello 66666666 World_This is a Regex Demo Extra stings
content = 'Extra stings Hello 1234567 World_This is a Regex Demo Extra stings'#要替换的内容是在包含原字符串的本身后面去追加
content = re.sub('(\d+)',r'\1 3333', content) #\1保留原始字符串 r表示追加 空格后面表示要追加的内容
print(content)
Extra stings Hello 1234567 3333 World_This is a Regex Demo Extra stings
| 表示或
将阻碍匹配的数据替换成空白
方便后面的匹配
re.compile()
将正则字符串编译成正则表达式对象
content = '''Hello 1234567 world_This
is a Regex Demo
'''pattern = re.compile('Hello.*?Demo', re.S) #正则表达式对象
print(pattern)result = re.match(pattern, content)
print(result)
re.compile('Hello.*?Demo', re.DOTALL)
<re.Match object; span=(0, 40), match='Hello 1234567 world_This\nis a Regex Demo'>
