一 基本知识

millisecond 毫秒
microsecond 微秒
nanosecond 纳秒
1秒=1000毫秒 1毫秒=1000微秒 1微秒=1000纳秒

二 perl

perl中可以使用time或localtime来获得时间，time返回从1970年1月1日0点的秒数，localtime返回当前时间的字符串表示，或者年月日等得tuple表示。

#!/usr/bin/perl
use strict;
use warnings;
use POSIX qw(strftime);

# seconds from 1970.01.01 00:00:00
my $ti = time();
print $ti;
print \"\\n\";
print strftime(\"%Y-%m-%d %H:%M:%S\\n\", localtime($ti));
#1310623469
#2011-07-14 14:03:58

my $t = localtime();
print $t;
print \"\\n\";
#Thu Jul 14 12:25:16 2011

my ($sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $isdst)=localtime();
print $year;
print \"\\n\";
#111

print strftime(\"%Y-%m-%d %H:%M:%S\\n\", localtime());
#2011-07-14 12:26:01

三 c#
1tick = 100 nanosecond

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace MyTest
{
  class Program
  {
    static void DateTimeTest()
    {
      DateTime dt2 = DateTime.Now;
      Console.WriteLine(dt2.Ticks);
      Console.WriteLine(dt2.ToString(\"MM/dd/yyyy hh:mm:ss\"));
    }

    static DateTime? ConvertPerlTimeToDateTime(string perltime)
    {
      DateTime? dt = null;
      //perl time variable : seconds from 1970.01.01 00:00:00 
      string sdt = perltime;
      long ldt = 0;
      if (long.TryParse(sdt, out ldt))
      {
        long ldt2 = new DateTime(1970, 1, 1).Ticks + ldt * 1000 * 1000 * 10;
         dt = new DateTime(ldt2, DateTimeKind.Local);
        Console.WriteLine(dt.Value.ToString(\"MM/dd/yyyy hh:mm:ss\"));
      }
      return dt;
    }

    static void Main(string[] args)
    {
      DateTimeTest();
      ConvertPerlTimeToDateTime(\"1309423883\");
      //634462479788396720
      //07/14/2011 01:46:18
      //06/30/2011 08:51:23
    }
  }
}

四 python

python的perl相似，time也是从1970年1月1日开始的秒数。

import time

ISOTIMEFORMAT=\'%Y-%m-%d %X\'

# seconds from 1970.01.01 00:00:00
t = time.time()
print (t)
print time.strftime(ISOTIMEFORMAT,time.localtime(t))
#1310623143.12
#2011-07-14 13:59:03

(year,mon,day,hour,min,sec,wday,yday,isdst) = time.localtime()
print (year)
print (time.strftime(ISOTIMEFORMAT, time.localtime()))
#2011
#2011-07-14 13:59:03