得到毫秒的时间

Question

我需要从计时器获得毫秒

    // get timer part
    time_t timer = time(NULL);
    struct tm now = *localtime( &timer );
    char timestamp[256];

    // format date time
    strftime(timestamp, sizeof(timestamp), "%Y-%m-%d_%H.%M.%S", &now);

我希望在C#中得到这样的结果:

DateTime.Now.ToString("yyyy-MM-dd_HH.mm.ss.ff")

我尝试使用%f或%F,但它确实适用于C++.如何从tm获得%f的毫秒数？

提前致谢

Answer 1

#include <chrono>

typedef std::chrono::system_clock Clock;

auto now = Clock::now();
auto seconds = std::chrono::time_point_cast<std::chrono::seconds>(now);
auto fraction = now - seconds;
time_t cnow = Clock::to_time_t(now);

然后,您可以使用秒精度打印出time_t,然后打印分数所代表的任何内容.可能是毫秒,微秒或其他东西.要专门获得毫秒:

auto milliseconds = std::chrono::duration_cast<std::chrono::milliseconds>(fraction);
std::cout << milliseconds.count() << '\n';

Answer 2

在Windows上使用Win32 API SYSTEMTIME结构将为您提供毫秒.然后,您应该使用时间函数来获取时间.像这样:

#include <windows.h>

int main()
{
    SYSTEMTIME stime;
    //structure to store system time (in usual time format)
    FILETIME ltime;
    //structure to store local time (local time in 64 bits)
    FILETIME ftTimeStamp;
    char TimeStamp[256];//to store TimeStamp information
    GetSystemTimeAsFileTime(&ftTimeStamp); //Gets the current system time

    FileTimeToLocalFileTime (&ftTimeStamp,&ltime);//convert in local time and store in ltime
    FileTimeToSystemTime(&ltime,&stime);//convert in system time and store in stime

    sprintf(TimeStamp, "%d:%d:%d:%d, %d.%d.%d",stime.wHour,stime.wMinute,stime.wSecond, 
            stime.wMilliseconds, stime.wDay,stime.wMonth,stime.wYear);

    printf(TimeStamp);

    return 0;
} 

Answer 3

这是另一个 c++11 答案：

#include <iostream>
#include <iomanip>
#include <chrono>
#ifdef WIN32
#define localtime_r(_Time, _Tm) localtime_s(_Tm, _Time)
#endif

int main()
{
    tm localTime;
    std::chrono::system_clock::time_point t = std::chrono::system_clock::now();
    time_t now = std::chrono::system_clock::to_time_t(t);
    localtime_r(&now, &localTime);

    const std::chrono::duration<double> tse = t.time_since_epoch();
    std::chrono::seconds::rep milliseconds = std::chrono::duration_cast<std::chrono::milliseconds>(tse).count() % 1000;

    std::cout << (1900 + localTime.tm_year) << '-'
        << std::setfill('0') << std::setw(2) << (localTime.tm_mon + 1) << '-'
        << std::setfill('0') << std::setw(2) << localTime.tm_mday << ' '
        << std::setfill('0') << std::setw(2) << localTime.tm_hour << ':'
        << std::setfill('0') << std::setw(2) << localTime.tm_min << ':'
        << std::setfill('0') << std::setw(2) << localTime.tm_sec << '.'
        << std::setfill('0') << std::setw(3) << milliseconds
        << std::endl;
}

Answer 4

有getimeofday()函数.以ms为单位返回时间请点击此处:http://souptonuts.sourceforge.net/code/gettimeofday.c.html