如何从 .NET DateTime 中截断毫秒-C#/.NET问题

How to truncate milliseconds off of a .NET DateTime(如何从 .NET DateTime 中截断毫秒)

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问题描述

我正在尝试将来自传入请求的时间戳与数据库存储值进行比较.SQL Server 当然在时间上保持一些毫秒的精度，当读入 .NET DateTime 时，它包括那些毫秒.然而，传入系统的请求并没有提供这种精度，所以我需要简单地减少毫秒数.

I'm trying to compare a time stamp from an incoming request to a database stored value. SQL Server of course keeps some precision of milliseconds on the time, and when read into a .NET DateTime, it includes those milliseconds. The incoming request to the system, however, does not offer that precision, so I need to simply drop the milliseconds.

我觉得我遗漏了一些明显的东西，但我还没有找到一种优雅的方式来做到这一点 (C#).

I feel like I'm missing something obvious, but I haven't found an elegant way to do it (C#).

推荐答案

以下将适用于具有小数毫秒的 DateTime，并且还保留 Kind 属性(Local、Utc 或 Undefined).

The following will work for a DateTime that has fractional milliseconds, and also preserves the Kind property (Local, Utc or Undefined).

DateTime dateTime = ... anything ...
dateTime = new DateTime(
    dateTime.Ticks - (dateTime.Ticks % TimeSpan.TicksPerSecond), 
    dateTime.Kind
    );

或同等或更短的:

dateTime = dateTime.AddTicks( - (dateTime.Ticks % TimeSpan.TicksPerSecond));

这可以概括为扩展方法:

This could be generalized into an extension method:

public static DateTime Truncate(this DateTime dateTime, TimeSpan timeSpan)
{
    if (timeSpan == TimeSpan.Zero) return dateTime; // Or could throw an ArgumentException
    if (dateTime == DateTime.MinValue || dateTime == DateTime.MaxValue) return dateTime; // do not modify "guard" values
    return dateTime.AddTicks(-(dateTime.Ticks % timeSpan.Ticks));
}

具体用法如下:

dateTime = dateTime.Truncate(TimeSpan.FromMilliseconds(1)); // Truncate to whole ms
dateTime = dateTime.Truncate(TimeSpan.FromSeconds(1)); // Truncate to whole second
dateTime = dateTime.Truncate(TimeSpan.FromMinutes(1)); // Truncate to whole minute
...

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