You can use the Add method to add more than one kind of time interval (days, hours, minutes, seconds, or milliseconds) in a single operation. This method's behavior is identical to that of the addition operator. The DateTime structure also supports specialized addition methods (such as AddDays, AddHours, and AddMinutes) for each time interval.
The Add method takes into account leap years and the number of days in a month when performing date arithmetic.
This method does not change the value of this DateTime. Instead, it returns a new DateTime whose value is the result of this operation. The Kind property of the new DateTime instance is the same as that of the current instance.
Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)