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
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.