Question

我想得到一个系统的毫秒时间（我不在乎它是否是实时的，我希望它尽可能准确）。这是一个很好的方法吗？

#ifdef WIN32
unsigned long long freq;
unsigned long long get_ms_time() {
    LARGE_INTEGER t;
    QueryPerformanceCounter(&t);
    return t.QuadPart / freq;
}
#else
unsigned long long get_ms_time() {
    struct timespec t;
    clock_gettime(CLOCK_MONOTONIC, &t);
    return t.tv_sec * 1000 + t.tv_nsec / 1000000;
}
#endif

如何将此值包装到signed int？我尝试这样做，我得到这样的负值（在Linux上，我不知道在Windows上）：

~ start
-2083002438
~ 15 seconds after..
-2082987440
~ 15 seconds after..
-2082972441

我会喜欢这样的。〜开始 X ......之后~15秒 X + 14998 ......之后~15秒 X + 29997

其中X是正数。（我希望输出为正且增加）

Answer 1

我在我的代码中做了类似的事情......

timespec specStart, specStop;

// Get start time ( UNIX timestamp ) in seconds...
clock_gettime( CLOCK_MONOTONIC_RAW, &startTime );

int startTimeInt = startTime.tv_sec;
std::cout << "start time : " << startTimeInt << std::endl;

...
// Get stop time ( UNIX timestamp ) in seconds...
clock_gettime( CLOCK_MONOTONIC_RAW, &stopTime );

int stopTimeInt = stopTime.tv_sec;
std::cout << "stop time : " << stopTimeInt << std::endl;

// Get time diff from stop time to start time
unsigned long long timeStart = specStart.tv_sec * 1000000000 + specStart.tv_nsec;
unsigned long long timeStop = specStop.tv_sec * 1000000000 + specStop.tv_nsec;
unsigned long long timeDelta = timeStio - timeStart; // Time diff in nanoseconds. 

int microSec = timeDelate / 1000; 
int mSec = timeDelta / 1000000;
int sec = timeDelta / 1000000000;

std::cout << "time diff : " << std::endl
    << sec << " s" << std::endl
    << msec << " ms" << std::endl
    << microSec << " µs" << std::endl
    << timeDelta << " ns" << std::endl;

Linux和Windows毫秒时间

1 个答案: