Match^ match = Regex::Match("one two three", "one (.*) three");
if (match->Success) Console::WriteLine("{0}", match->Groups[1]->Captures[0]);

using namespace System;
using namespace System::Text::RegularExpressions;

int main()
{
Match^ match = Regex::Match("one two three", "one (.*) three");
if (match->Success) Console::WriteLine("{0}", match->Groups[1]->Captures[0]);
}

cmatch what;
if (regex_match("one two three", what, regex("one (.*) three")))
cout << what[1] << endl;

// must link with boost_regex or boost_regex-mt (multithread-safe) library

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

using namespace std;
using namespace boost;

int main()
{
cmatch what;
if (regex_match("one two three", what, regex("one (.*) three")))
cout << what[1] << endl;
}