//Using c++11 regex to tokenize input string
  //[0-9]+ = 1 or many digits
  //Or [\-\+\\(\)\/\*] = "-" or "+" or "/" or "*" or "(" or ")"
  std::regex e ( "[0-9]+|[\-\+\\(\)\/\*]");
  std::sregex_iterator rend;
  std::sregex_iterator a( infixExpression.begin(), infixExpression.end(), e );

  queue<string> infixQueue;
  while (a!=rend) {
      infixQueue.push(a->str());
      ++a;
  }
  return infixQueue;

tring infix; //The string to be parse (the arithmetic operation if you will)
vector<string> untokenize;
std::regex words_regex("[0-9]?([0-9]*[.])?[0-9]+|[\-\+\\(\)\/\*]");
auto words_begin = std::sregex_iterator(infix.begin(), infix.end(), words_regex);
auto words_end = std::sregex_iterator();

for (std::sregex_iterator i = words_begin; i != words_end; ++i) {
    cout << (*i).str() << endl;
    untokenize.push_back((*i).str());
}