c# - 为什么这两个 DateTime 实例不同？

Question

考虑以下(简化的)代码:

DateTime now   = DateTime.Now;
DateTime now2  = new DateTime(now.Year, now.Month, now.Day,
                              now.Hour, now.Minute, now.Second,
                              now.Millisecond, now.Kind);
bool condition = (now <= now2);

由于我已将 now 的字段复制到 now2，因此 DateTime 结构的这两个实例应该相等。但是，condition 的计算结果为 false。为什么？

有什么方法可以更改代码以使条件计算为真吗？

Answer 1

It's the Ticks .它总是蜱虫。有时。

DateTime now = DateTime.Now;
DateTime now2 = new DateTime(now.Year, now.Month, now.Day,
    now.Hour, now.Minute, now.Second, now.Millisecond);
bool condition = (now <= now2);

var diff = now2 - now;

时间分辨率小于毫秒。 Ticks is the real value :

The value of this property represents the number of 100-nanosecond intervals that have elapsed since 12:00:00 midnight, January 1, 0001 (0:00:00 UTC on January 1, 0001, in the Gregorian calendar), which represents DateTime.MinValue.

它有一个构造函数:

var reallyNow = new Datetime(now.Ticks);

您从未将 Ticks 的任何值传递给 now2 的构造函数(因为它没有参数)，所以 now2.Ticks 末尾将有四个零。但是，您直接复制到 now 的 DateTime.Now 确实有一个不能被 10,000 整除的 Ticks 值。