NAME

SYNOPSIS

#include <pcre++.h>

Detailed Description

The library 'pcre++' defines a class named 'Pcre' which you can use to search in strings using reular expressions as well as getting matched sub strings. It does currently not support all features, which the underlying PCRE library provides, but the most important stuff is implemented.

Please study this example code to learn how to use this class:

/*
 *
 *  This file  is part of the PCRE++ Class Library.
 *
 *  By  accessing  this software,  PCRE++, you  are  duly informed
 *  of and agree to be  bound  by the  conditions  described below
 *  in this notice:
 *
 *  This software product,  PCRE++,  is developed by Thomas Linden
 *  and  copyrighted (C) 2002  by  Thomas Linden,  with all rights 
 *  reserved.
 *
 *  There  is no charge for PCRE++ software.  You can redistribute
 *  it and/or modify it under the terms of the GNU  Lesser General
 *  Public License, which is incorporated by reference herein.
 *
 *  PCRE++ is distributed WITHOUT ANY WARRANTY, IMPLIED OR EXPRESS,
 *  OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE or that
 *  the use of it will not infringe on any third party's intellec-
 *  tual property rights.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with PCRE++.  Copies can also be obtained from:
 *
 *    http://www.gnu.org/licenses/lgpl.txt
 *
 *  or by writing to:
 *
 *  Free Software Foundation, Inc.
 *  59 Temple Place, Suite 330
 *  Boston, MA 02111-1307
 *  USA
 *
 *  Or contact:
 *
 *   'Thomas Linden' <tom@daemon.de>
 *
 *
 */
/* you need to include the pcre++ header file */
#include <pcre++.h>
#include <iostream>
using namespace std;
void regex() {
    /*
     * define a string with a regular expression
     */
    string expression = '([a-z]*) ([0-9]+)';
    /*
     * this is the string in which we want to search
     */
    string stuff = 'hallo 11 robert';
    cout << '  searching in ´' << stuff << '´ for regex ´'
         << expression << '´:' << endl;
    /*
     * Create a new Pcre object, search case-insensitive ('i')
     */
    Pcre reg(expression, 'i');
    
    /*
     * see if the expression matched
     */
    if(reg.search(stuff) == true) {
      /*
       * see if the expression generated any substrings
       */
      if(reg.num_matches >= 1) {
        /*
         * print out the number of substrings
         */
        cout << '  generated ' << reg.matches() << ' substrings:' << endl;
          
        /*
         * iterate over the matched sub strings
         */
        for(int pos=0; pos < reg.matches(); pos++) {
          /* print out each substring */
          cout << '  substring ' << pos << ': ' << reg.get_match(pos);
          /* print out the start/end offset of the current substring
           * within the searched string(stuff)
           */
          cout << ' (start: ' << reg.get_match_start(pos) << ', end: '
               << reg.get_match_end(pos) << ')' << endl;
        }
      }
      else {
        /*
         * we had a match, but it generated no substrings, for whatever reason
         */
        cout << '   it matched, but there where no substrings.' << endl;
      }
    }
    else {
      /*
       * no match at all
       */
      cout << '   didn't match.' << endl;
    }
}
void replace() {
    /*
     * Sample of replace() usage
     */
    string orig = 'Hans ist 22 Jahre alt. Er ist 8 Jahre älter als Fred.';
    cout << '   orig: ' << orig << endl;
    /*
     * define a regex for digits (character class)
     */
    Pcre p(' ([0-9]+) ');
    /*
     * replace the 1st occurence of [0-9]+ with 'zweiundzwanzig'
     */
    string n = p.replace(orig, ' zweiundzwanzig($1) ');
    /*
     * prints out: 'Hans ist zweiundzwanzig Jahre alt. Er ist 8 Jahre älter
     * als Fred.'
     */
    cout << '   new: ' << n << endl; 
}
void replace_multi() {
  /*
   * Sample of replace() usage with multiple substrings
   */
  string orig = ' 08:23 ';
  cout << '   orig: ' << orig << endl;
  
  /*
   * create regex which, if it matches, creates 3 substrings
   */
  Pcre reg(' ([0-9]+)(:)([0-9]+) ', 'sig');
  /*
   * remove $2 (':')
   * re-use $1 ('08') and $3 ('23') in the replace string
   */
  string n  = reg.replace(orig, '$1 Stunden und $3 Minuten');
  /*
   * prints the result: '08 Stunden und 23 Minuten'
   */
  cout << '   new:  ' << n  << endl;
}
void normalize() {
  /*
   * another sample to check if normalizing using replace() works
   */
  string orig = 'Heute   ist ein  schoener  Tag        gell?';
  cout << '   orig: ' << orig << endl;
  /*
   * create regex for normalizing whitespace
   */
  Pcre reg('[\s]+', 'gs');
  /*
   * do the normalizing process
   */
  string n = reg.replace(orig, ' ');
  /*
   * prints the result, should be: 'Heute ist ein schoener Tag , gell?'
   */
  cout << '   new:  ' << n  << endl;
}
void split() {
  /*
   * Sample of split() usage
   */
      string sp_orig = 'was21willst2387461du3alter!';
      cout << '   orig: ' << sp_orig << endl;
      /*
       * define a regex for digits (character class)
       */
      string delimiter = '[0-9]+';
      /*
       * new Pcre object, match globally ('g' flag)
       */
      Pcre S(delimiter, 'g');
      /*
       * split 'was21willst2387461du3alter!' by digits
       */
      Array splitted = S.split(sp_orig);
      
      /*
       * iterate over the resulting list
       */
      cout << '   splitted: ';
      for(ArrayIterator A = splitted.begin(); A != splitted.end(); ++A)
        cout << *A << ' ';
      cout << endl;
}
void ex() {
  /*
   * Pcre::exception Test
   */
  
  /*
   * this will generate only one substring, 'This'
   */
  Pcre ex('([a-z]+)', 'i');
  if(ex.search('This is a test.')) {
    cout << '  trying to access a non-existing substring:' << endl;
    cout << '  substring 2: ' << ex.get_match(1) << endl; 
  }
}
void mycopy() {
  /*
   * Sample use of copy contsructor and operator=
   */
    cout << '  initializing reg1(([a-z]+?)' << endl;
    Pcre reg1('^([a-z]+?)');
    /*
     * create an empty Pcre objects
     */
    Pcre reg2;
    
    /*
     * copy reg1 to reg2 (operator=)
     */
    cout << '  copying reg1 to new Pcre object reg2' << endl;
    reg2 = reg1;
    /*
     * using the copy constructor to initialize the 3rd object
     */
    cout << '  creating a new Pcre object reg3 from reg2' << endl;
    Pcre reg3(reg2);
    /*
     * doing regular stuff on reg3
     */
    if(reg3.search('anton'))
      cout << '  string 'anton' matched using reg3 object' << endl;
}
void multisearch() {
  Pcre reg('([^\n]+\n)');
  string str = '0ine10ine20ine30;
  size_t pos = 0;
  while (pos <= str.length()) {
    if( reg.search(str, pos)) {
      pos = reg.get_match_end(0);
      cout << '   pos: ' << pos << ' match: ' << reg.get_match(0);
    }
    else
      break;
  }
}
int main() {
  /* 
   * the Pcre class throws errors via exceptions
   */
  try {
    cout << endl << 'SEARCH() sample:' << endl;
    regex();
    cout << endl << 'REPLACE() sample:' << endl;
    replace();
    cout << endl << 'Multiple REPLACE() sample:' << endl;
    replace_multi();
    cout << endl << 'Normalizing REPLACE() sample:' << endl;
    normalize();
    cout << endl << 'SPLIT() sample:' << endl;
    split();
    cout << endl << 'COPY+Operator sample:' << endl;
    mycopy();
    cout << endl << 'Multi line search test:' << endl;
    multisearch();
    cout << endl << 'Pcre::exception test:' << endl;
    ex();
    exit(0);
  }
  catch (Pcre::exception &E) {
    /*
     * the Pcre class has thrown an exception
     */
    cerr << 'Pcre++ error: ' << E.what() << endl;
    exit(-1);
  }
  exit(0);
}
  

Compile your programs which use the prce++ class using the following command line: 

   g++ -c yourcode.o `pcre-config --cflags` `pcre++-config --cflags`
   g++ yourcode.o `pcre-config --libs` `pcre++-config --libs` -o yourprogram
 

If you want to learn more about regular expressions which can be used with pcre++, then please read the following documentation: perlre - Perl regular expressions

The pcre library itself does also contain some usefull documentation, which maybe interesting for you: PCRE manual page 

Definition at line 95 of file pcre++.h.

Constructor & Destructor Documentation

Member Function Documentation

 
 std::string mysub = regex.get_match(1); 
 
 

Get the first substring that metched the expression in the 'regex' object. 

Definition at line 59 of file get.cc.

References ArrayIterator, and num_matches.

 Pcre regex('([0-9]+)-z]+)');     // search for the date(makes 2 substrings
 regex.search('The 11th september.');  // do the search on this string
 int pos = regex.get_match_end();      // returns 17, because '11th september', which is
                                           // the entire match, ends at the
                                       // 17th character inside the search string.
 

See also:

int get_match_start() 

int get_match_start(int pos) 

int get_match_end(int pos) 

Definition at line 76 of file get.cc.

Referenced by replace().

 Pcre regex('([0-9]+)');               // search for numerical characters
 regex.search('The 11th september.');  // do the search on this string
 std::string day = regex.get_match(1);      // returns '11'
 int pos = regex.get_match_end(1);     // returns 5, because '11' ends at the
                                       // 5th character inside the search string.
 

See also:

int get_match_start(int pos) 

int get_match_start() 

int get_match_end() 

Definition at line 95 of file get.cc.

References num_matches.

 Pcre regex('([0-9]+)-z]+)');     // search for the date(makes 2 substrings
 regex.search('The 11th september.');  // do the search on this string
 int pos = regex.get_match_start();    // returns 4, because '11th september' begins at the
                                       // 4th character inside the search string.
 

See also:

int get_match_start(int pos) 

int get_match_end(int pos) 

int get_match_end() 

Definition at line 69 of file get.cc.

Referenced by replace().

 
 Pcre regex('([0-9]+)');               // search for numerical characters
 regex.search('The 11th september.');  // do the search on this string
 std::string day = regex.get_match(1);      // returns '11'
 int pos = regex.get_match_start(1);   // returns 4, because '11' begins at the
                                       // 4th character inside the search string.
 

See also:

int get_match_end(int pos) 

int get_match_end() 

int get_match_start() 

Definition at line 83 of file get.cc.

References num_matches.

 Pcre reg1('^[a-z]+?');
 Pcre reg2;
 reg2 = reg1;
 

Definition at line 132 of file pcre++.cc.

References _expression, _flags, case_t, and global_t.

 Pcre regex = '(A+?)';
 

Definition at line 121 of file pcre++.cc.

Member Data Documentation

Author