#include <functional>
#include <iostream>
#include <regex>
#include <string>
using namespace std;
int main()
{
string const input = "The quick brown fox.";
std::regex const words("[^\\s]+");
auto f = std::mem_fn(&std::smatch::str);
std::sregex_iterator i = std::sregex_iterator(input.begin(), input.end(), words);
std::smatch m = *i;
string first_word = f(m, 0);
return 0;
}
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