How can I clone a DateTime object in C#?

Question

如何在C＃中克隆DateTime对象？

Answer 1

DateTime is a value type ( struct )

This means that the following creates a copy:

DateTime toBeClonedDateTime = DateTime.Now;
DateTime cloned = toBeClonedDateTime;

You can also safely do things like:

var dateReference = new DateTime(2018, 7, 29);
for (var h = 0; h < 24; h++) {
  for (var m = 0; m < 60; m++) {
    var myDateTime = dateReference.AddHours(h).AddMinutes(m);
    Console.WriteLine("Now at " + myDateTime.ToShortDateString() + " " + myDateTime.ToShortTimeString());
  }
}

Note how in the last example myDateTime gets declared anew in each cycle; if dateReference had been affected by AddHours() or AddMinutes() , myDateTime would've wandered off really fast – but it doesn't, because dateReference stays put:

Now at 2018-07-29 0:00
Now at 2018-07-29 0:01
Now at 2018-07-29 0:02
Now at 2018-07-29 0:03
Now at 2018-07-29 0:04
Now at 2018-07-29 0:05
Now at 2018-07-29 0:06
Now at 2018-07-29 0:07
Now at 2018-07-29 0:08
Now at 2018-07-29 0:09
...
Now at 2018-07-29 23:55
Now at 2018-07-29 23:56
Now at 2018-07-29 23:57
Now at 2018-07-29 23:58
Now at 2018-07-29 23:59

Answer 2

var original = new DateTime(2010, 11, 24);
var clone = original;

DateTime is a value type, so when you assign it you also clone it. That said, there's no point in cloning it because it's immutable; typically you'd only clone something if you had the intention of changing one of the copies.

Answer 3

DateTime is a value type so everytime you assign it to a new variable you are cloning.

DateTime foo = DateTime.Now;
DateTime clone = foo;