Regex: Invalid preceding regular expression problem
Hello, I'm a new member to the mailing list. BTW, thanks to everyone who contributes to boost. It's a fantastic software. I am having a problem with building an expression object. The line in question reads 'boost::regex expression(pattern, options);', where I'm using the boost::regex::extended option, and the pattern looks like this: "^([0-7]\\..*|8\\.0(\\.[0-3](\\.[0-3])?)?)[^.0-9]*?$". I fired up a ruby interpreter, and it handled the regex fine (using "8.0.0.1 (en-US)" as a positive, and "9.0.0.1 (en-US)" as a negative). Can anybody tell me what is wrong with this regex, or confirm that there may be a bug in the library? thanks, brian
Brian Krahmer wrote:
Hello, I'm a new member to the mailing list. BTW, thanks to everyone who contributes to boost. It's a fantastic software. I am having a problem with building an expression object. The line in question reads 'boost::regex expression(pattern, options);', where I'm using the boost::regex::extended option, and the pattern looks like this: "^([0-7]\\..*|8\\.0(\\.[0-3](\\.[0-3])?)?)[^.0-9]*?$". I fired up a ruby interpreter, and it handled the regex fine (using "8.0.0.1 (en-US)" as a positive, and "9.0.0.1 (en-US)" as a negative). Can anybody tell me what is wrong with this regex, or confirm that there may be a bug in the library?
Nope there's a bug in the options you are using - boost::regex::extended enables the "POSIX extended" flavour of regular expressions - and these don't support non-greedy repeats. Use boost::regex::perl if you want to use these (since you are using Perl-style regexes). HTH, John.
participants (2)
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Brian Krahmer -
John Maddock