Timestamp with milliseconds

timestampWithMs.cpp

#include <chrono>
#include <iomanip>
#include <iostream>

string getTimestamp() {
  // get a precise timestamp as a string
  const auto now = std::chrono::system_clock::now();
  const auto nowAsTimeT = std::chrono::system_clock::to_time_t(now);
  const auto nowMs = std::chrono::duration_cast<std::chrono::milliseconds>(
      now.time_since_epoch()) % 1000;
  std::stringstream nowSs;
  nowSs
      << std::put_time(std::localtime(&nowAsTimeT), "%a %b %d %Y %T")
      << '.' << std::setfill('0') << std::setw(3) << nowMs.count();
  return nowSs.str();
}