DateAndTime.DateAdd DateAndTime.DateAdd DateAndTime.DateAdd DateAndTime.DateAdd Method

Definition

Returns a Date value containing a date and time value to which a specified time interval has been added.

Overloads

DateAdd(DateInterval, Double, DateTime) DateAdd(DateInterval, Double, DateTime) DateAdd(DateInterval, Double, DateTime) DateAdd(DateInterval, Double, DateTime)

Returns a value containing a date and time value to which a specified time interval has been added.

DateAdd(String, Double, Object) DateAdd(String, Double, Object) DateAdd(String, Double, Object) DateAdd(String, Double, Object)

Returns a value containing a date and time value to which a specified time interval has been added.

DateAdd(DateInterval, Double, DateTime) DateAdd(DateInterval, Double, DateTime) DateAdd(DateInterval, Double, DateTime) DateAdd(DateInterval, Double, DateTime)

Returns a value containing a date and time value to which a specified time interval has been added.

public:
 static DateTime DateAdd(Microsoft::VisualBasic::DateInterval Interval, double Number, DateTime DateValue);
public static DateTime DateAdd (Microsoft.VisualBasic.DateInterval Interval, double Number, DateTime DateValue);
static member DateAdd : Microsoft.VisualBasic.DateInterval * double * DateTime -> DateTime
Public Function DateAdd (Interval As DateInterval, Number As Double, DateValue As DateTime) As DateTime

Parameters

Interval
DateInterval DateInterval DateInterval DateInterval

Required. A DateInterval enumeration value or a string expression representing the time interval you want to add.

Number
Double Double Double Double

Required. Floating-point expression representing the number of intervals you want to add. It can be positive (to get date/time values in the future) or negative (to get date/time values in the past). It can contain a fractional part when Interval specifies hours, minutes, or seconds. For other values of Interval, any fractional part of Number is ignored.

DateValue
DateTime DateTime DateTime DateTime

Required. An expression representing the date and time to which the interval is to be added. DateValue itself is not changed in the calling program.

Returns

A value containing a date and time value to which a specified time interval has been added.

Exceptions

Calculated date is before 00:00:00 on January 1 of the year 1, or later than 23:59:59 on December 31, 9999.

Examples

This example takes a date and, using the DateAdd function, displays a corresponding date a specified number of months in the future.

Dim dateEntered As String =
InputBox("Enter a date", DefaultResponse:=Date.Now.ToShortDateString)
Dim monthsEntered As String =
InputBox("Enter number of months to add", DefaultResponse:="12")

Dim dateValue As Date = Date.Parse(dateEntered)
Dim monthsValue As Integer = Integer.Parse(monthsEntered)

' Add the months to the date.
Dim newDate As Date = DateAdd(DateInterval.Month, monthsValue, dateValue)

' This statement has a string interval argument, and
' is equivalent to the above statement.
'Dim newDate As Date = DateAdd("m", monthsValue, dateValue)

MessageBox.Show("New date: " & newDate.ToShortDateString)

Remarks

You can use the DateAdd function to add or subtract a specified time interval from a date. For example, you can calculate a date 30 days from today or a time 45 minutes before now.

To add days to DateValue, you can use DateInterval.Day, DateInterval.DayOfYear, or DateInterval.Weekday. These are treated as equivalent because DayOfYear and Weekday are not meaningful time intervals.

The DateAdd function never returns an invalid date. If necessary, the day part of the resulting date is adjusted downward to the last day of the resulting month in the resulting year. The following example adds one month to January 31:

Dim NextMonth As Date = DateAdd(DateInterval.Month, 1, #1/31/1995#)  

In this example, DateAdd returns #2/28/1995#, not #2/31/1995#. If DateValue is #1/31/1996#, it returns #2/29/1996# because 1996 is a leap year.

Note

DateAdd uses the current calendar setting from the CurrentCulture property of the CultureInfo class in the System.Globalization namespace. The default CurrentCulture values are determined by Control Panel settings.

Since every Date value is supported by a DateTime structure, its methods give you additional options in adding time intervals. For example, you can add a fractional number of days, rounded to the nearest millisecond, to a Date variable as follows:

Dim NextTime As Date = Now        ' Current date and time.  
NextTime = NextTime.AddDays(3.4)  ' Increment by 3 2/5 days.  

The Interval argument can have one of the following settings.

Enumeration value String Unit of time interval to add
DateInterval.Day d Day; truncated to integral value
DateInterval.DayOfYear y Day; truncated to integral value
DateInterval.Hour h Hour; rounded to nearest millisecond
DateInterval.Minute n Minute; rounded to nearest millisecond
DateInterval.Month m Month; truncated to integral value
DateInterval.Quarter q Quarter; truncated to integral value
DateInterval.Second s Second; rounded to nearest millisecond
DateInterval.Weekday w Day; truncated to integral value
DateInterval.WeekOfYear ww Week; truncated to integral value
DateInterval.Year yyyy Year; truncated to integral value
See also

DateAdd(String, Double, Object) DateAdd(String, Double, Object) DateAdd(String, Double, Object) DateAdd(String, Double, Object)

Returns a value containing a date and time value to which a specified time interval has been added.

public:
 static DateTime DateAdd(System::String ^ Interval, double Number, System::Object ^ DateValue);
public static DateTime DateAdd (string Interval, double Number, object DateValue);
static member DateAdd : string * double * obj -> DateTime
Public Function DateAdd (Interval As String, Number As Double, DateValue As Object) As DateTime

Parameters

Interval
String String String String

Required. A DateInterval enumeration value or a string expression representing the time interval you want to add.

Number
Double Double Double Double

Required. Floating-point expression representing the number of intervals you want to add. Number can be positive (to get date/time values in the future) or negative (to get date/time values in the past). It can contain a fractional part when Interval specifies hours, minutes, or seconds. For other values of Interval, any fractional part of Number is ignored.

DateValue
Object Object Object Object

Required. An expression representing the date and time to which the interval is to be added. DateValue itself is not changed in the calling program.

Returns

A value containing a date and time value to which a specified time interval has been added.

Exceptions

Calculated date is before 00:00:00 on January 1 of the year 1, or later than 23:59:59 on December 31, 9999.

Examples

This example takes a date and, using the DateAdd function, displays a corresponding date a specified number of months in the future.

Dim dateEntered As String =
InputBox("Enter a date", DefaultResponse:=Date.Now.ToShortDateString)
Dim monthsEntered As String =
InputBox("Enter number of months to add", DefaultResponse:="12")

Dim dateValue As Date = Date.Parse(dateEntered)
Dim monthsValue As Integer = Integer.Parse(monthsEntered)

' Add the months to the date.
Dim newDate As Date = DateAdd(DateInterval.Month, monthsValue, dateValue)

' This statement has a string interval argument, and
' is equivalent to the above statement.
'Dim newDate As Date = DateAdd("m", monthsValue, dateValue)

MessageBox.Show("New date: " & newDate.ToShortDateString)

Remarks

You can use the DateAdd function to add or subtract a specified time interval from a date. For example, you can calculate a date 30 days from today or a time 45 minutes before now.

To add days to DateValue, you can use DateInterval.Day, DateInterval.DayOfYear, or DateInterval.Weekday. These are treated as equivalent because DayOfYear and Weekday are not meaningful time intervals.

The DateAdd function never returns an invalid date. If necessary, the day part of the resulting date is adjusted downward to the last day of the resulting month in the resulting year. The following example adds one month to January 31:

Dim NextMonth As Date = DateAdd(DateInterval.Month, 1, #1/31/1995#)  

In this example, DateAdd returns #2/28/1995#, not #2/31/1995#. If DateValue is #1/31/1996#, it returns #2/29/1996# because 1996 is a leap year.

Note

DateAdd uses the current calendar setting from the CurrentCulture property of the CultureInfo class in the System.Globalization namespace. The default CurrentCulture values are determined by Control Panel settings.

Since every Date value is supported by a DateTime structure, its methods give you additional options in adding time intervals. For example, you can add a fractional number of days, rounded to the nearest millisecond, to a Date variable as follows:

Dim NextTime As Date = Now        ' Current date and time.  
NextTime = NextTime.AddDays(3.4)  ' Increment by 3 2/5 days.  

The Interval argument can have one of the following settings.

Enumeration value String Unit of time interval to add
DateInterval.Day d Day; truncated to integral value
DateInterval.DayOfYear y Day; truncated to integral value
DateInterval.Hour h Hour; rounded to nearest millisecond
DateInterval.Minute n Minute; rounded to nearest millisecond
DateInterval.Month m Month; truncated to integral value
DateInterval.Quarter q Quarter; truncated to integral value
DateInterval.Second s Second; rounded to nearest millisecond
DateInterval.Weekday w Day; truncated to integral value
DateInterval.WeekOfYear ww Week; truncated to integral value
DateInterval.Year yyyy Year; truncated to integral value
See also

Applies to