XML parsing with regex, C++ (gcc)

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

using namespace std;

int main ()
{
  string s ("<?info?> <tag1 key1> <tag2 key2>contents2</tag2> <tag3> contents 3</tag3> <tag4 key contents/> </tag1>");
  smatch m;
  regex e ("<(/*)(\\S+?)\\b(.*?)(/*)>"); // try to match <tag key> or <tag> or </tag> or <tag key/>, where
                                         // capture group 1: / - closing slash at the beginning of the short tag as in </tag>
                                         // capture group 2: tag - as in <tag key>
                                         // capture group 3: key - as in <tag key>
                                         // capture group 4: / - closing slash at the end of the of the long tag as in <tag key value/>

while (regex_search (s,m,e, regex_constants::match_any)) // provide override default settings with POSIX, where extended mode (e.g. lazy quantifiers are not supported)
  {
    int i = 0;
    for (auto x:m) 
    {
        if(i == 0)        
            cout << "\nWhole match: ";
        else
            cout << "\nCapture group " << i << ": ";
        cout << x << " ";
        i++;
    }
    cout << "\n=================================\n";
    s = m.suffix().str();
    
  }

return 0;
}

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