问题
Could someone please help me to use gettimeofday() function with Visual Studio C++ 2008 on Windows XP? here is a code that I found somewhere on the net:
#include < time.h >
#include <windows.h>
#if defined(_MSC_VER) || defined(_MSC_EXTENSIONS)
#define DELTA_EPOCH_IN_MICROSECS 11644473600000000Ui64
#else
#define DELTA_EPOCH_IN_MICROSECS 11644473600000000ULL
#endif
struct timezone
{
int tz_minuteswest; /* minutes W of Greenwich */
int tz_dsttime; /* type of dst correction */
};
int gettimeofday(struct timeval *tv, struct timezone *tz)
{
FILETIME ft;
unsigned __int64 tmpres = 0;
static int tzflag;
if (NULL != tv)
{
GetSystemTimeAsFileTime(&ft);
tmpres |= ft.dwHighDateTime;
tmpres <<= 32;
tmpres |= ft.dwLowDateTime;
/*converting file time to unix epoch*/
tmpres -= DELTA_EPOCH_IN_MICROSECS;
tmpres /= 10; /*convert into microseconds*/
tv->tv_sec = (long)(tmpres / 1000000UL);
tv->tv_usec = (long)(tmpres % 1000000UL);
}
if (NULL != tz)
{
if (!tzflag)
{
_tzset();
tzflag++;
}
tz->tz_minuteswest = _timezone / 60;
tz->tz_dsttime = _daylight;
}
return 0;
}
...
// call gettimeofday()
gettimeofday(&tv, &tz);
tm = localtime(&tv.tv_sec);
Last year when I tested this code with VC++6, it worked fine. But now as I use VC++ 2008, I am getting error of exception handling. So is there any idea on how to use gettimeofday or something equivalent?
Thanks for your reply and any help would be very appreciated:
回答1:
In UNIX the use of the timezone struct is obsolete. I don't know why you use it. See http://linux.about.com/od/commands/l/blcmdl2_gettime.htm But if you want to use this structure to know about GMT(UTC) diffrence from your local time it will be next: tz_minuteswest is the real diffrence in minutes from GMT(UTC) and a tz_dsttime is a flag indicates whether daylight is now in use.
Your example with some changes works fine in Visual C++ 2008 Express:
#include "stdafx.h"
#include <time.h>
#include <windows.h>
const __int64 DELTA_EPOCH_IN_MICROSECS= 11644473600000000;
/* IN UNIX the use of the timezone struct is obsolete;
I don't know why you use it. See http://linux.about.com/od/commands/l/blcmdl2_gettime.htm
But if you want to use this structure to know about GMT(UTC) diffrence from your local time
it will be next: tz_minuteswest is the real diffrence in minutes from GMT(UTC) and a tz_dsttime is a flag
indicates whether daylight is now in use
*/
struct timezone2
{
__int32 tz_minuteswest; /* minutes W of Greenwich */
bool tz_dsttime; /* type of dst correction */
};
struct timeval2 {
__int32 tv_sec; /* seconds */
__int32 tv_usec; /* microseconds */
};
int gettimeofday(struct timeval2 *tv/*in*/, struct timezone2 *tz/*in*/)
{
FILETIME ft;
__int64 tmpres = 0;
TIME_ZONE_INFORMATION tz_winapi;
int rez=0;
ZeroMemory(&ft,sizeof(ft));
ZeroMemory(&tz_winapi,sizeof(tz_winapi));
GetSystemTimeAsFileTime(&ft);
tmpres = ft.dwHighDateTime;
tmpres <<= 32;
tmpres |= ft.dwLowDateTime;
/*converting file time to unix epoch*/
tmpres /= 10; /*convert into microseconds*/
tmpres -= DELTA_EPOCH_IN_MICROSECS;
tv->tv_sec = (__int32)(tmpres*0.000001);
tv->tv_usec =(tmpres%1000000);
//_tzset(),don't work properly, so we use GetTimeZoneInformation
rez=GetTimeZoneInformation(&tz_winapi);
tz->tz_dsttime=(rez==2)?true:false;
tz->tz_minuteswest = tz_winapi.Bias + ((rez==2)?tz_winapi.DaylightBias:0);
return 0;
}
int _tmain(int argc, _TCHAR* argv[])
{
struct timeval2 tv;
struct timezone2 tz;
struct tm *tm1;
time_t time1;
ZeroMemory(&tv,sizeof(tv));
ZeroMemory(&tz,sizeof(tz));
gettimeofday(&tv, &tz); // call gettimeofday()
time1=tv.tv_sec;
tm1 = localtime(&time1);
FILE *f;
f=fopen("rez.txt","w");
fprintf(f,"%04d.%02d.%02d %02d:%02d:%02d\n",1900+tm1->tm_year,1+tm1->tm_mon,tm1->tm_mday,tm1->tm_hour,tm1->tm_min,tm1->tm_sec);
fprintf(f,"Diffrence between GMT(UTC) and local time=%d %s\n",tz.tz_minuteswest,"minutes");
fprintf(f,"Is Daylight now=%s\n",tz.tz_dsttime?"Yes":"No");
fclose(f);
return 0;
}
回答2:
Simple stopwatch in seconds
FWIW: This is a similar one as that of Kate, but I just wanted to mention it, if someone is looking for the most simple stopwatch in C++ (counting seconds). Not a big deal, I know. It has only resolution of 1 sec, so if you want to cound microsecs, go on with the other examples.
double seconds=0;
time_t timer1, timer2;
time(&timer1); /* get current time */
...
time(&timer2); /* get current time later */
seconds = difftime(timer2,timer1);
回答3:
There are a few different types to represent a time. Here's some code I used recently:
time_t now;
tm* local;
time(&now);
local=localtime(&now);
I then went on to build a string from pieces of local
, but you could do what you wanted at this point.
Kate
来源:https://stackoverflow.com/questions/2494356/how-to-use-gettimeofday-or-something-equivalent-with-visual-studio-c-2008