拆分字串
std::vector<std::string> split(const std::string &str, std::string regex)
{
std::regex r{ regex };
std::sregex_token_iterator start{ str.begin(), str.end(), r, -1 }, end;
return std::vector<std::string>(start, end);
}
split("Some string\t with whitespace ", "\\s+"); // "Some", "string", "with", "whitespace"