Thread: Matching regular expressions in c++

Hi all

I have the following problem. I am using PERL language to read text file, and in this file I use pattern matching to search for specific line formatting. I need this because I am analyzing big code output.
For instance if I look for line such as
44.333e-02 44.221e-03 22.332e-04

I can define in PERL

Code:

if($line=~/(\d{2}\.\d{3}e-\d{2}) +(\d{2}\.\d{3}e-\d{2}) +(\d{2}\.\d{3}e\d{2})/)
{
$a[$i++]=$1 ;

$B[$j++]=$2 ;

$C[$k++]=$3 ;

}

Where $1,$2,$3 are perl notation to say what is matched in the first second third bracket . This shall store the desired objects matched in the above specified pattern in @A,@B,@C arrays.
Is it possible to do this in C++. In ordinary C there are functions regcomp() regexec() which are an option but are rather complicated compared with the simple perl procedure.

Thank you in advance

This is ok, but can't I manage my goal with standard package libraries. Because after all I would like to do it as simple as possible.

Well first of all thank you for the very professional opinion. I installed the boost.regex library but got problems compiling c++ code which uses it. I used the following command to compile my code

Code:

g++ -o ZZ test.cpp –I/home/boost/boost_1_45_0/libs/regex/build/gcc/boost_regex-gcc-1_45/ -L/home/boost/boost_1_45_0/libs/regex/build/gcc/libboost_regex-gcc-1_45.a

In short I am giving the paths to de library and the includes . However it does not run. The actual code i compile is : (code downloaded form the internet)

Code:

#include <iostream>
#include <string>
#include <boost/regex.hpp>

using namespace std;

int main( ) {

   std::string s, sre;
   boost::regex re;

   while(true)
   {
      cout << "Expression: ";
      cin >> sre;
      if (sre == "quit")
      {
         break;
      }
      cout << "String:     ";
      cin >> s;

      try
      {
         // Set up the regular expression for case-insensitivity
         re.assign(sre, boost::regex_constants::icase);
      }
      catch (boost::regex_error& e)
      {
         cout << sre << " is not a valid regular expression: \""
              << e.what() << "\"" << endl;
         continue;
      }
      if (boost::regex_match(s, re))
      {
         cout << re << " matches " << s << endl;
      }
   }
}

Does anyone knows why this does not work?


The actual error reads as follows

Code:

ccYuUtqf.o: In function `boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits<char> > >::assign(char const*, char const*, unsigned int)':
test.cpp:(.text._ZN5boost11basic_regexIcNS_12regex_traitsIcNS_16cpp_regex_traitsIcEEEEE6assignEPKcS7_j[boost::basic_regex<char, boost::regex_traits<char, boost::cpp_regex_traits'
/home/tmp/ccYuUtqf.o: In function `boost::re_detail::perl_matcher<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator:
test.cpp:(.text._ZN5boost9re_detail12perl_matcherIN9__gnu_cxx17__normal_iteratorIPKcSsEESaINS_9sub_matchIS6_EEENS_12regex_traitsIcNS_16cpp_regex_traitsIcEEEEEC1ES6_S6_RNS_13matc'
/home/tmp/ccYuUtqf.o:(.gcc_except_table+0xa4): undefined reference to `typeinfo for boost::regex_error'
/home/tmp/ccYuUtqf.o: In function `bool boost::regex_match<__gnu_cxx::__normal_iterator<char const*, std::basic_string<char, std::char_traits<char>, std::allocator<char> :
test.cpp:(.text._ZN5boost11regex_matchIN9__gnu_cxx17__normal_iteratorIPKcSsEESaINS_9sub_matchIS5_EEEcNS_12regex_traitsIcNS_16cpp_regex_traitsIcEEEEEEbT_SD_RNS_13match_resultsISD'
collect2: ld returned 1 exit status