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DateTime.AddDays Method

Adds the specified number of days to the value of this instance.

[Visual Basic]
Public Function AddDays( _
   ByVal value As Double _
) As DateTime
public DateTime AddDays(
 double value
public: DateTime AddDays(
 double value
public function AddDays(
   value : double
) : DateTime;


A number of whole and fractional days. The value parameter can be negative or positive.

Return Value

A DateTime whose value is the sum of the date and time represented by this instance and the number of days represented by value.


Exception Type Condition
ArgumentOutOfRangeException The resulting DateTime is less than MinValue or greater than MaxValue.


This method does not change the value of this DateTime. Instead, a new DateTime is returned whose value is the result of this operation.

The fractional part of value is the fractional part of a day. For example, 4.5 is equivalent to 4 days, 12 hours, 0 minutes, 0 seconds, 0 milliseconds, and 0 ticks.

The value parameter is rounded to the nearest tick.


[Visual Basic, C#, C++] The following sample demonstrates the AddDays method.

[Visual Basic] 
' Calculate what day of the week is 36 days from this instant.
Dim today As System.DateTime
Dim answer As System.DateTime

today = System.DateTime.Now
answer = today.AddDays(36)

System.Console.WriteLine("{0:dddd}", answer)

// Calculate what day of the week is 36 days from this instant.
System.DateTime today = System.DateTime.Now;
System.DateTime answer = today.AddDays(36);
System.Console.WriteLine("{0:dddd}", answer);

// Calculate what day of the week is 36 days from this instant.
System::DateTime today = System::DateTime::Now;
System::DateTime answer = today.AddDays(36);
System::Console::WriteLine(S"{0:dddd}", __box(answer));

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.


Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework, Common Language Infrastructure (CLI) Standard

See Also

DateTime Structure | DateTime Members | System Namespace | Double