int main()
{ 
    time_t ltime;
    time(&ltime);
    cout<<ctime(&time);
    return 0;
}

#include<stdio.h> 　　
#include <stddef.h> 　　
#include <time.h> 　　
int main(void) 　　
{
    time_t timer;  //time_t就是long int 类型
     struct tm *tblock;
    timer = time(NULL);//这一句也可以改成time(&timer);
    tblock = localtime(&timer);
    printf("Local time is: %s\n",asctime(tblock));
    return 0; 　　
}

 //time_t是世界时间， 比 本地时间 少8小时(即28800秒)
 double seconds = 1259666013 + 28800;
 double secs = Convert.ToDouble(seconds);
 DateTime dt = new DateTime(
 1970, 1, 1, 0, 0, 0, DateTimeKind.Unspecified).AddSeconds(secs);
 //TimeSpan span = 
 //        TimeSpan.FromTicks(seconds*TimeSpan.TicksPerSecond); 
  Console.WriteLine(dt);

public static long DateTimeToTime_t(DateTime dateTime)
{
   long time_t;
   DateTime dt1 = new DateTime(1970, 1, 1,0,0,0);
   TimeSpan ts =dateTime - dt1;
   time_t = ts.Ticks/10000000-28800;      
   return time_t;
}

static void Main(string[] args)
{
   DateTime dateTime = new DateTime(2009,12,1,19,13,33);
   Console.WriteLine(DateTimeToTime_t(dateTime));
}