সি++ [123] রেজেক্স

#include <iostream>
#include <string>
#include <regex>
using namespace std;

int main() {

  std::string text = "a1b2c3";
  std::regex pattern("[12]");

  for (std::sregex_iterator it(text.begin(), text.end(), pattern), end;
    it != end; ++it) {
    std::cout << it->str() << std::endl;
  }
}