转义行情 - 如何转义加号

如何解决转义行情 - 如何转义加号

import re

这是我的尝试

note = r"Call \[phone]\.Midnight"

或

note = "Call [phone].Midnight"

然后

print(re.search("[phone]",note))

错误

---------------------------------------------------------------------------
error                                     Traceback (most recent call last)
~/Desktop/modules/regular_exp.py in 
     12 note = "Call [phone].Midnight"
     13 
---> 14 print(re.search("[phone]",note))

/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/re.py in search(pattern,string,flags)
    199     """Scan through string looking for a match to the pattern,returning
    200     a Match object,or None if no match was found."""
--> 201     return _compile(pattern,flags).search(string)
    202 
    203 def sub(pattern,repl,count=0,flags=0):

/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/re.py in _compile(pattern,flags)
    302     if not sre_compile.isstring(pattern):
    303         raise TypeError("first argument must be string or compiled pattern")
--> 304     p = sre_compile.compile(pattern,flags)
    305     if not (flags & DEBUG):
    306         if len(_cache) >= _MAXCACHE:

/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/sre_compile.py in compile(p,flags)
    762     if isstring(p):
    763         pattern = p
--> 764         p = sre_parse.parse(p,flags)
    765     else:
    766         pattern = None

/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/sre_parse.py in parse(str,flags,state)
    946 
    947     try:
--> 948         p = _parse_sub(source,state,flags & SRE_FLAG_VERBOSE,0)
    949     except Verbose:
    950         # the VERBOSE flag was switched on inside the pattern.  to be

/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/sre_parse.py in _parse_sub(source,verbose,nested)
    441     start = source.tell()
    442     while True:
--> 443         itemsappend(_parse(source,nested + 1,444                            not nested and not items))
    445         if not sourcematch("|"):

/Library/Frameworks/Python.framework/Versions/3.9/lib/python3.9/sre_parse.py in _parse(source,nested,first)
    666                 item = None
    667             if not item or item[0][0] is AT:
--> 668                 raise source.error("nothing to repeat",669                                    source.tell() - here + len(this))
    670             if item[0][0] in _REPEATCODES:

error: nothing to repeat at position 0

解决方法

note = r"Call \[phone]\.Midnight"
print(re.search("[phone]",note))

需要转义的不是搜索字符串，而是正则表达式。如果您将尝试的转义应用于 search 的第一个参数而不是 note：

note = "Call [phone].Midnight"
print(re.search(r"\[phone]",note))

输出：

<re.Match object; span=(5,18),match='[phone]'>