Time stamp for saving file or folder?

Is there a simpler way to do a time stamp for saving a file/creating a directory as a date time stamp ? only using standard library (not boost). Is there a faster way to do it ?

This is my current code

std::chrono::system_clock::time_point now = std::chrono::system_clock::now();
std::time_t tt = std::chrono::system_clock::to_time_t(now);
tm utc_tm = *gmtime(&tt);   
oname.str("");
oname << (utc_tm.tm_year + 1900) << '-' << std::setfill('0') << std::setw(2) << (utc_tm.tm_mon + 1) << '-' << std::setfill('0') << std::setw(2) << utc_tm.tm_mday << "  " << std::setfill('0') << std::setw(2)<< utc_tm.tm_hour <<':' <<  std::setfill('0') << std::setw(2) << utc_tm.tm_min <<':' <<  std::setfill('0') << std::setw(2) << utc_tm.tm_sec;
ts = oname.str();