C++: what regex library should I use?

I'm working on a commercial (not open source) C++ project that runs on a linux-based system. I need to do some regex within the C++ code. (I know: I now have 2 problems.)

QUESTION: What libraries do people who regularly do regex from C/C++ recommend I look into? A quick search has brought the following to my attention:

1. Boost.Regex (I need to go read the Boost Software License, but this question is not about software licenses)

2. C (not C++) POSIX regex (#include <regex.h>, regcomp, regexec, etc.)

3. http://freshmeat.net/projects/cpp_regex/ (I know nothing about this one; seems to be GPL, therefore not usable on this project)

Boost.Regex is very good and is slated to become part of the C++0x standard (it's already in TR1).

Personally, I find Boost.Xpressive much nicer to work with. It is a header-only library and it has some nice features such as static regexes (regexes compiled at compile time).

Update: If you're using a C++11 compliant compiler (gcc 4.8 is NOT!), use std::regex unless you have good reason to use something else.

Thanks for all the suggestions.

I tried out a few things today, and with the stuff we're trying to do, I opted for the simplest solution where I don't have to download any other 3rd-party library. In the end, I #include <regex.h> and used the standard C POSIX calls regcomp() and regexec(). Not C++, but in a pinch this proved to be the easiest.

In C++ projects past, I have used PCRE with good success. It's very complete and well-tested since it's used in many high profile projects. And I see that Google has contributed a set of C++ wrappers for PCRE recently, too.

C++ has a builtin regex library since TR1. AFAIK Boost's regex library is very compatible with it and can be used as a replacement, if your standard library doesn't provide TR1.

Boost has http://www.boost.org/doc/libs/1_36_0/libs/regex/doc/html/index.html">regex in it.

That should fill the bill

Two more options:

If you can write it in c++11 - Do the tutorial: http://www.codeguru.com/cpp/cpp/cpp_mfc/stl/article.php/c15339

Note: At the time of writing the only c++11 regex library that I know works is the clang/llvm one, and only works on Mac. The GNU still doesn't implement regex yet. I don't know about Visual Studio. Most people still use the boost regex implementation.

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Or you can use ragel to generate a finite state machine to do the parsing for you, and generate the C/C++ code implementation: http://www.complang.org/ragel/

I used it a little to generate code to parse json. This ragel file: https://github.com/matiu2/yajp/blob/master/parser/number.rl is used to generate this code https://github.com/matiu2/yajp/blob/master/parser/json.hpp#L254 and this finite state machine diagram:

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Update 1:

lvm's libc++ regex works on ubuntu 14.04: libc++-dev - LLVM C++ Standard library (development files). When compiling: clang++ -std=c++11 -lc++ -I/usr/include/c++/v1 ...

Update 2:

I'm currently enjoying boost spirit 3 - I like it more than regex, because it has BNF style rules and is well thought out. (Older (more documented) Spirit Qi libs found here)

You can also look at fast regex library that was developed at Yandex search engine for doing fast matches of thousands of patterns against huge amounts of data.

I've personally always used boost.regex (although I don't have much need for regex in C++). Microsoft Labs has a regex library too, called GRETA: http://research.microsoft.com/projects/greta/. Apparently it's very fast and features a whole Perl 5 syntax. I haven't used it, but you may want to test it out.

I faced a similar situation and ended up using Henry Spencers Regexp Engine http://www.codeproject.com/KB/string/spencerregexp.aspx

Noone here said anything about the one that comes with C++0x. If you are using a compiler and the STL that supports C++0x you could just use that instead of having another lib in your project.