How do you remove parentheses words within a string using NSRegularExpression?
I am not t开发者_如何学Gooo familiar with regex and so I been having some getting this to work with Apple's NSRegularExpression
I am trying to remove words in parentheses or brackets...
For example:
NSString *str = @"How do you (remove parentheses words) within a string using"
resulting string should be: @"How do you within a string using"
Thanks you!!!
Search for
\([^()]*\)
and replace with nothing.
As a verbose regex:
\( # match an opening parenthesis
[^()]* # match any number of characters except parentheses
\) # match a closing parenthesis
This will work fine if parentheses are correctly balanced and unnested. If parentheses can be nested (like this (for example))
, then you need to re-run the replace until there are no further matches, since only the innermost parentheses will be matched in each run.*
To remove brackets, do the same with \[[^[\]]*\]
, for braces \{[^{}]*\}
.
With conditional expressions you could do all three at once, but the regex looks ugly, doesn't it?
(?:(\()|(\[)|(\{))[^(){}[\]]*(?(1)\))(?(2)\])(?(3)\})
However, I'm not sure if NSRegularExpression can handle conditionals. Probably not. Explanation of this monster:
(?: # start of non-capturing group (needed for alternation)
(\() # Either match an opening paren and capture in backref #1
| # or
(\[) # match an opening bracket into backref #2
| # or
(\{) # match an opening brace into backref #3
) # end of non-capturing group
[^(){}[\]]* # match any number of non-paren/bracket/brace characters
(?(1)\)) # if capturing group #1 matched before, then match a closing parenthesis
(?(2)\]) # if #2 matched, match a closing bracket
(?(3)\}) # if #3 matched, match a closing brace.
*You can't match arbitrarily nested parentheses (since these constructs are no longer regular) with regular expressions, so that's not a limitation of this regex in particular but of regexes in general.
I don't know objectice-c
regex flavor but in PCRE you can do :
s/\[.*?\]|\(.*?\)|\{.*?\}//g
This will replace everything between parentheses or brackets by empty string.
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