Boost: How to print/convert posix_time::ptime in milliseconds from Epoch?

I am having trouble converting posix_time::ptime to a timestamp represented by time_t or posix_time::milliseconds, or any other appropriate type which can be开发者_运维技巧 easily printed (from Epoch).

I actually need just to print the timestamp represented by the posix_time::ptime in milliseconds, so if there is an easy way to print in that format, I don't actually need the conversion.

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This code will print the number of milliseconds since 1941-12-07T00:00:00. Obviously, you can choose whatever epoch suits your need.

void print_ptime_in_ms_from_epoch(const boost::posix_time::ptime& pt)
  {
    using boost::posix_time::ptime;
    using namespace boost::gregorian;
    std::cout << (pt-ptime(date(1941, Dec, 7))).total_milliseconds() << "\n";
  }