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正则-函数 ​

  • 正则表达式操作的包为import re

match ​

  • 语法：re.match(pattern, string)
  • 只从字符串的开头开始匹配模式，如果匹配成功，返回一个匹配对象，否则返回 None
python
import re

pattern = '12'
string = '123456456'
match_obj = re.match(pattern, string)
print(match_obj)  # <re.Match object; span=(0, 2), match='12'>

pattern = '34'
string = '123456456'
match_obj = re.match(pattern, string)
print(match_obj)  # None
  • 语法：re.search(pattern, string)
  • 搜索整个字符串，返回第一个匹配的对象，否则返回 None
python
import re

pattern = '56'
string = '123456456'
match_obj = re.search(pattern, string)
print(match_obj)  # <re.Match object; span=(4, 6), match='56'>

pattern = '58'
string = '123456456'
match_obj = re.search(pattern, string)
print(match_obj)  # None

findall ​

  • 语法：re.findall(pattern, string)
  • 搜索整个字符串，返回所有匹配的对象，否则返回 None
python
import re

pattern = '56'
string = '123456456'
match_obj = re.findall(pattern, string)
print(match_obj)  # ['56', '56']

sub ​

  • 语法：re.sub(pattern, repl, string)
  • 搜索整个字符串，将所有匹配的对象替换为指定的字符串，否则返回 None
python
import re

pattern = '56'
string = '123456456'
match_obj = re.sub(pattern, '88', string)
print(match_obj)  # 123488488

split ​

  • 语法：re.split(pattern, string)
  • 搜索整个字符串，将所有匹配的对象作为分隔符，将字符串分割为一个列表，否则返回 None
python
import re

pattern = '56'
string = '123456456'
match_obj = re.split(pattern, string)
print(match_obj)  # ['1234', '4', '']