Regex Fetching Various results with regex_search

Question

I just want to fetch results of a given string

#include <regex>
#include <iostream>
#include <string>

#include <conio.h>
using namespace std;

int main () {
   std::tr1::cmatch res;
   string str;
   str = "a lot of unknown text here<h2>Test2 12</h2> a lot of unknown text here <h2>Test3 45</h2>a lot of text here too";
   std::tr1::regex rx("Test(\d+) (\\d+)");
   std::tr1::regex_search(str.c_str(), res, rx);
   std::cout << "RES 1: " << res[1] << ". " << res[2] << "\n";
   std::cout << "RES 2: " <<  res[3] << ". " << res[4] << "\n";
   return 0;
}

I want it to be able to get from one search the results of both, example:

Array 1: [1] = 2, [2] = 12 and Array 2: [1] = 3, [2] = 45 or it could be like this: [1] = 2, [2] = 12, [3] = 3, [4] = 45

how do I do that? If I'm using the incorrect function, tell me which function and how to use it to do what I asked here. I hope I was clear enough, Thanks in advance.

Marcin Hoppe · Accepted Answer · 2012-03-22 18:55:56Z

What you're looking for is regex_iterator class template. In your example:

#include <regex>
#include <iostream>
#include <string>

int main () {
    std::string str("a lot of unknown text here<h2>Test2 12</h2> a lot of unknown text here <h2>Test3 45</h2>a lot of text here too");
    std::tr1::regex rx("Test(\\d+) (\\d+)");
    std::tr1::sregex_iterator first(str.begin(), str.end(), rx);
    std::tr1::sregex_iterator last;

    for (auto it = first; it != last; ++it) 
    {
        std::cout << "[1]=" << it->str(1) << " [2]=" << it->str(2) << std::endl;
    }

    return 0;
}

Also, you can implement your option number 2 with regex_token_iterator class template:

#include <regex>
#include <iostream>
#include <string>

int main () 
{
    std::string str("a lot of unknown text here<h2>Test2 12</h2> a lot of unknown text here <h2>Test3 45</h2>a lot of text here too");
    std::tr1::regex rx("Test(\\d+) (\\d+)");
    int fields[2] = { 1, 2 };
    std::tr1::sregex_token_iterator first(str.begin(), str.end(), rx, fields);
    std::tr1::sregex_token_iterator last;

    std::size_t i = 0;
    for (auto it = first; it != last; ++it) 
    {
        std::cout << "[" << i << "]=" << it->str() << std::endl;
        ++i;
    }

    return 0;
}

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