DateTime.AddHours Method (Double)
Returns a new DateTime that adds the specified number of hours to the value of this instance.
Assembly: mscorlib (in mscorlib.dll)
A number of whole and fractional hours. The value parameter can be negative or positive.
Return ValueType: System.DateTime
An object whose value is the sum of the date and time represented by this instance and the number of hours represented by value.
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 returned DateTime object is the same as that of value.
The fractional part of value is the fractional part of an hour. For example, 4.5 is equivalent to 4 hours, 30 minutes, 0 seconds, 0 milliseconds, and 0 ticks.
The value parameter is rounded to the nearest millisecond.
Converting time intervals of less than an hour to a fraction can involve a loss of precision if the result is a non-terminating repeating decimal. (For example, one minute is 0.016667 of an hour.) If this is problematic, you can use the Add method, which enables you to specify more than one kind of time interval in a single method call and eliminates the need to convert time intervals to fractional parts of an hour.
The following example uses themethod to add a number of whole and fractional values to a date and time. It also illustrates the loss of precision caused by passing the method a value that includes a fractional component.
Available since 8
Available since 1.1
Portable Class Library
Supported in: portable .NET platforms
Available since 2.0
Windows Phone Silverlight
Available since 7.0
Available since 8.1