DateTime.AddHours(Double) Method
Definition
Important
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Returns a new DateTime that adds the specified number of hours to the value of this instance.
public:
DateTime AddHours(double value);
public DateTime AddHours (double value);
member this.AddHours : double -> DateTime
Public Function AddHours (value As Double) As DateTime
Parameters
- value
- Double
A number of whole and fractional hours. The value
parameter can be negative or positive.
Returns
An object whose value is the sum of the date and time represented by this instance and the number of hours represented by value
.
Exceptions
The resulting DateTime is less than DateTime.MinValue or greater than DateTime.MaxValue.
Examples
The following example uses the AddHours method 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.
using System;
public class Example
{
public static void Main()
{
double[] hours = {.08333, .16667, .25, .33333, .5, .66667, 1, 2,
29, 30, 31, 90, 365};
DateTime dateValue = new DateTime(2009, 3, 1, 12, 0, 0);
foreach (double hour in hours)
Console.WriteLine("{0} + {1} hour(s) = {2}", dateValue, hour,
dateValue.AddHours(hour));
}
}
// The example displays the following output on a system whose current
// culture is en-US:
// 3/1/2009 12:00:00 PM + 0.08333 hour(s) = 3/1/2009 12:04:59 PM
// 3/1/2009 12:00:00 PM + 0.16667 hour(s) = 3/1/2009 12:10:00 PM
// 3/1/2009 12:00:00 PM + 0.25 hour(s) = 3/1/2009 12:15:00 PM
// 3/1/2009 12:00:00 PM + 0.33333 hour(s) = 3/1/2009 12:19:59 PM
// 3/1/2009 12:00:00 PM + 0.5 hour(s) = 3/1/2009 12:30:00 PM
// 3/1/2009 12:00:00 PM + 0.66667 hour(s) = 3/1/2009 12:40:00 PM
// 3/1/2009 12:00:00 PM + 1 hour(s) = 3/1/2009 1:00:00 PM
// 3/1/2009 12:00:00 PM + 2 hour(s) = 3/1/2009 2:00:00 PM
// 3/1/2009 12:00:00 PM + 29 hour(s) = 3/2/2009 5:00:00 PM
// 3/1/2009 12:00:00 PM + 30 hour(s) = 3/2/2009 6:00:00 PM
// 3/1/2009 12:00:00 PM + 31 hour(s) = 3/2/2009 7:00:00 PM
// 3/1/2009 12:00:00 PM + 90 hour(s) = 3/5/2009 6:00:00 AM
// 3/1/2009 12:00:00 PM + 365 hour(s) = 3/16/2009 5:00:00 PM
open System
let hours =
[ 0.08333; 0.16667; 0.25
0.33333; 0.5; 0.66667; 1
2; 29; 30; 31; 90; 365 ]
let dateValue = DateTime(2009, 3, 1, 12, 0, 0)
for hour in hours do
printfn $"{dateValue} + {hour} hour(s) = {dateValue.AddHours hour}"
// The example displays the following output on a system whose current
// culture is en-US:
// 3/1/2009 12:00:00 PM + 0.08333 hour(s) = 3/1/2009 12:04:59 PM
// 3/1/2009 12:00:00 PM + 0.16667 hour(s) = 3/1/2009 12:10:00 PM
// 3/1/2009 12:00:00 PM + 0.25 hour(s) = 3/1/2009 12:15:00 PM
// 3/1/2009 12:00:00 PM + 0.33333 hour(s) = 3/1/2009 12:19:59 PM
// 3/1/2009 12:00:00 PM + 0.5 hour(s) = 3/1/2009 12:30:00 PM
// 3/1/2009 12:00:00 PM + 0.66667 hour(s) = 3/1/2009 12:40:00 PM
// 3/1/2009 12:00:00 PM + 1 hour(s) = 3/1/2009 1:00:00 PM
// 3/1/2009 12:00:00 PM + 2 hour(s) = 3/1/2009 2:00:00 PM
// 3/1/2009 12:00:00 PM + 29 hour(s) = 3/2/2009 5:00:00 PM
// 3/1/2009 12:00:00 PM + 30 hour(s) = 3/2/2009 6:00:00 PM
// 3/1/2009 12:00:00 PM + 31 hour(s) = 3/2/2009 7:00:00 PM
// 3/1/2009 12:00:00 PM + 90 hour(s) = 3/5/2009 6:00:00 AM
// 3/1/2009 12:00:00 PM + 365 hour(s) = 3/16/2009 5:00:00 PM
Module Example
Public Sub Main()
Dim hours() As Double = {.08333, .16667, .25, .33333, .5, .66667, 1, 2, _
29, 30, 31, 90, 365}
Dim dateValue As Date = #3/1/2009 12:00#
For Each hour As Double In hours
Console.WriteLine("{0} + {1} hour(s) = {2}", dateValue, hour, _
dateValue.AddHours(hour))
Next
End Sub
End Module
' The example displays the following output on a system whose current
' culture is en-US:
' 3/1/2009 12:00:00 PM + 0.08333 hour(s) = 3/1/2009 12:04:59 PM
' 3/1/2009 12:00:00 PM + 0.16667 hour(s) = 3/1/2009 12:10:00 PM
' 3/1/2009 12:00:00 PM + 0.25 hour(s) = 3/1/2009 12:15:00 PM
' 3/1/2009 12:00:00 PM + 0.33333 hour(s) = 3/1/2009 12:19:59 PM
' 3/1/2009 12:00:00 PM + 0.5 hour(s) = 3/1/2009 12:30:00 PM
' 3/1/2009 12:00:00 PM + 0.66667 hour(s) = 3/1/2009 12:40:00 PM
' 3/1/2009 12:00:00 PM + 1 hour(s) = 3/1/2009 1:00:00 PM
' 3/1/2009 12:00:00 PM + 2 hour(s) = 3/1/2009 2:00:00 PM
' 3/1/2009 12:00:00 PM + 29 hour(s) = 3/2/2009 5:00:00 PM
' 3/1/2009 12:00:00 PM + 30 hour(s) = 3/2/2009 6:00:00 PM
' 3/1/2009 12:00:00 PM + 31 hour(s) = 3/2/2009 7:00:00 PM
' 3/1/2009 12:00:00 PM + 90 hour(s) = 3/5/2009 6:00:00 AM
' 3/1/2009 12:00:00 PM + 365 hour(s) = 3/16/2009 5:00:00 PM
Remarks
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.
In .NET 6 and earlier versions, the value
parameter is rounded to the nearest millisecond. In .NET 7 and later versions, the full Double precision of the value
parameter is used. However, due to the inherent imprecision of floating point math, the resulting precision will vary.
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.
Applies to
See also
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