Compile and regex in c++ using eclipse

Question

So my professor gave me a work with regex in c++.

So I tried to write my code in eclipse (I am using linux (ubuntu 12.04)).

so I took the code :

   // regex_search example
#include <iostream>
#include <string>
#include <regex>

int main ()
{
  std::string s ("this subject has a submarine as a subsequence");
  std::smatch m;
  std::regex e ("\\b(sub)([^ ]*)");   // matches words beginning by "sub"

  std::cout << "Target sequence: " << s << std::endl;
  std::cout << "Regular expression: /\\b(sub)([^ ]*)/" << std::endl;
  std::cout << "The following matches and submatches were found:" << std::endl;

  while (std::regex_search (s,m,e)) {
    for (auto x:m) std::cout << x << " ";
    std::cout << std::endl;
    s = m.suffix().str();
  }

  return 0;
}

As you can see it is a simple code for working with regex.

so I try to build it and eclipse gives me an error:

Type 'smatch' could not be resolved

and also:

Type 'std::regex' could not be resolved

what is the problem ?

I tried to get add the flag -std=c++0x in the suitable location (properties->c/c++ build ->Miscellaneous)and nothing happen.

maybe I am doing it wrong ?

maybe I have to add a link to library like in pthread ?

You are probably using gcc 4.7.2 (or maybe the one before) with that version of Ubuntu? Regular expressions are not implemented in that version. (Not sure how far they have got right now. Last evidence I saw of any activity at all was some vague comments on a mailing list in January). — BoBTFish, May 23 '13 at 10:43
Consider [`Boost.Regex`](http://www.boost.org/doc/libs/1_53_0/libs/regex/doc/html/index.html). Ask your professor, they should know what they intend you to use. — BoBTFish, May 23 '13 at 10:45
Either change library to one with better support, or use [Boost regex](http://www.boost.org/doc/libs/1_53_0/libs/regex/doc/html/index.html) (which should be very compatible). — Some programmer dude, May 23 '13 at 10:46
@BoBTFish so you saying I can not use it ? I will have to use another library of regex ? — David Hamelech, May 23 '13 at 10:47
I've started using [clang](http://clang.llvm.org/) and it's [libc++](http://libcxx.llvm.org/) library, just because the C++11 support in GCC was lacking. — Some programmer dude, May 23 '13 at 10:51
@DavidHamelech Choosing and using another library (eg clang with libc++ or boost) is not something that can really be discussed in the comments. You need to ask your professor what they expect you to do. — BoBTFish, May 23 '13 at 10:51

score 4 · Answer 1 · edited Apr 17 '16 at 19:06

My setup:

Operation system: Ubuntu 14.04 Compiler: GCC 4.8.2 IDE: Eclipse 3.8.1

Problem:

I've included regex (#include <regex>) to my header file but my IDE keeps complaining that type of 'something' could not be resolved. I've tried using namespaces such as std:: and std::tr1, like people from google has adviced, with no success.

Solution:

Solution is as simple as the problem itself. If you take a look at usr/include/c++/4.8 you'll notice the regex file in root folder is kind of a stub. However there's another regex file in /tr1 folder.

The trick is, that instead of writing #include <regex>, you should write #include <tr1/regex>

After that you're able to use regex through std::tr1:: namespace.

For example like this: std::tr1::smatch

Hope that helps!

score 0 · Answer 2 · edited Jul 10 '13 at 12:01

0

regex is added under std::tr1 namespace. please declare the object for your regular expression as std::tr1::regex, it should work

edited Jul 10 '13 at 12:01

DevZer0

13,433
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answered Jul 10 '13 at 11:41

Zeeshan

1

1

Thanks DevZer0, but i really don't understand what is the actual change you have made except font change? – Zeeshan Jul 11 '13 at 04:16

score 0 · Answer 3 · edited May 23 '17 at 12:07

The flag is not enough, you have to add the preprocessor symbol " ____GXX_EXPERIMENTAL_CXX0X____" in "C/C++ General -> Paths and Symbols -> Symbols -> GNU C++" too. For details, please refer to the following question: Eclipse CDT C++11/C++0x support. It's also in the Eclipse wiki: http://wiki.eclipse.org/CDT/User/FAQ#CDT_does_not_recognize_C.2B.2B11_features. The second link also features an additional link to a forum page describing a "hidden" option (http://www.eclipse.org/forums/index.php/mv/msg/373462/909018/#msg_909018). If you configure the compiler with the "hidden" option as described in the link, it still works after removing the "____GXX_EXPERIMENTAL_CXX0X____" flag again. At least for me it worked this way (Eclipse Juno 4.2.2 and GCC 4.7.2).

Compile and regex in c++ using eclipse

3 Answers3