c# - 在 C# 中实现与 CTime.GetTime() 方法相同的行为

Question

我正在尝试在 C# 中实现 CTime::GetTime() 方法的行为。

这是我的控制台应用程序的代码片段(用 C++/CLI 编写):

int main(array<System::String ^> ^args)
{
 int epochYear = 1970;
 int epochMonth = 1;
 int epochDay = 1;

 DateTime managedEpochDate = DateTime(epochYear, epochMonth, epochDay);

 int year = 2013;
 int month = 2;
 int day = 13;
 int hour = 9;
 int minutes = 49;
 int seconds = 46;

 // DateTime/CTime -> Numeric Time (__time64_t)

 DateTime managedDateTime = DateTime(year, month, day, hour, minutes, seconds);
 CTime nativeDateTime = CTime(year, month, day, hour, minutes, seconds);

 DWORD nativeTimeToSerialize = nativeDateTime.GetTime();
 UInt32 managedTimeToSerialize = (managedDateTime - managedEpochDate)
     .TotalSeconds;
}

最后我有以下不同的值:

• nativeTimeToSerialize = 1360745386
• ma​​nagedTimeToSerialize = 1360748986

任何人都可以帮助我理解这种差异的原因吗？

Answer 1

不同之处在于 CTime constructor您正在使用将时间转换为 UTC:

This constructor makes the appropriate conversion to UTC.

而 DateTime在这种情况下，构造函数(和 other 一个)不知道时区:

The Kind property is initialized to DateTimeKind.Unspecified.

subtraction operator DateTime 也不考虑时区:

The Subtraction(DateTime, DateTime) method does not consider the value of the Kind property of the two DateTime values when performing the subtraction.

要获得所需的结果，请适本地设置 CTime 构造函数的最后一个参数，例如:

CTime nativeDateTime = CTime(year, month, day, hour, minutes, seconds, 0);

要修改 DateTime 用法，您需要:

int epochYear = 1970;
int epochMonth = 1;
int epochDay = 1;

DateTime managedEpochDateUtc
    = new DateTime(epochYear, epochMonth, epochDay, 0, 0, 0, DateTimeKind.Utc);

int year = 2013;
int month = 2;
int day = 13;
int hour = 9;
int minutes = 49;
int seconds = 46;

DateTime managedDateTimeLocal
    = new DateTime(year, month, day, hour, minutes, seconds, DateTimeKind.Local);

DateTime managedDateTimeUtc = managedDateTimeLocal.ToUniversalTime();

uint managedTimeToSerialize = (uint)(managedDateTimeUtc - managedEpochDateUtc)
 .TotalSeconds;

或者，按照 Mgetz 的建议你可以使用 DateTimeOffset而不是 DateTime，通常推荐使用 DateTime doesn't handle timezones very clearly .