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Calendar.AddMonths Method

When overridden in a derived class, returns a DateTime that is the specified number of months away from the specified DateTime.

Namespace:  System.Globalization
Assembly:  mscorlib (in mscorlib.dll)
'Declaration
Public MustOverride Function AddMonths ( _
	time As DateTime, _
	months As Integer _
) As DateTime

Parameters

time
Type: System.DateTime
The DateTime to which to add months.
months
Type: System.Int32
The number of months to add.

Return Value

Type: System.DateTime
The DateTime that results from adding the specified number of months to the specified DateTime.
ExceptionCondition
ArgumentException

The resulting DateTime is outside the supported range of this calendar.

ArgumentOutOfRangeException

months is outside the supported range of the DateTime return value.

The months value is added to the specified DateTime. If months is negative, the resulting DateTime is earlier than the specified DateTime.

The day part of the resulting DateTime is affected if the resulting day is not a valid day in the resulting month of the resulting year. It is changed to the last valid day in the resulting month of the resulting year. The year part of the resulting DateTime is affected if the resulting month is outside the year of the specified DateTime. The era part of the resulting DateTime is affected if the resulting year is outside the era of the specified DateTime. The time-of-day part of the resulting DateTime remains the same as the specified DateTime.

For example, suppose that the current calendar has 12 months, where the fourth month has 30 days and the tenth month has 31 days. If the specified month is the tenth month, the specified day is the 31st day of that month, and the value of the months parameter is 6, the resulting year is one more than the specified year, the resulting month is the fourth month, and the resulting day is the 30th day, which is the last day of the resulting month.

If the value of the months parameter is negative, the resulting DateTime is earlier than the specified DateTime.

The Kind property of the returned DateTime value always equals DateTimeKind.Unspecified. You can preserve the Kind property of the time parameter by calling the DateTime.SpecifyKind method, as the following example shows.


returnTime = DateTime.SpecifyKind(cal.AddMonths(time, months), time.Kind)


The following code example demonstrates the members of the Calendar class.


Imports System.Globalization

Public Class Example
   Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)

      ' Sets a DateTime to April 3, 2002 of the Gregorian calendar.
      Dim myDT As New DateTime(2002, 4, 3, New GregorianCalendar())

      ' Uses the default calendar of the InvariantCulture.
      Dim myCal As Calendar = CultureInfo.InvariantCulture.Calendar

      ' Displays the values of the DateTime.
      outputBlock.Text += String.Format("April 3, 2002 of the Gregorian calendar:") & vbCrLf
      DisplayValues(outputBlock, myCal, myDT)

      ' Adds 5 to every component of the DateTime.
      myDT = myCal.AddYears(myDT, 5)
      myDT = myCal.AddMonths(myDT, 5)
      myDT = myCal.AddWeeks(myDT, 5)
      myDT = myCal.AddDays(myDT, 5)
      myDT = myCal.AddHours(myDT, 5)
      myDT = myCal.AddMinutes(myDT, 5)
      myDT = myCal.AddSeconds(myDT, 5)
      myDT = myCal.AddMilliseconds(myDT, 5)

      ' Displays the values of the DateTime.
      outputBlock.Text &= "After adding 5 to each component of the DateTime:" & vbCrLf
      DisplayValues(outputBlock, myCal, myDT)

   End Sub 

   Public Shared Sub DisplayValues(ByVal outputBlock As System.Windows.Controls.TextBlock, ByVal myCal As Calendar, ByVal myDT As DateTime)
      outputBlock.Text += String.Format("   Era:          {0}", myCal.GetEra(myDT)) & vbCrLf
      outputBlock.Text += String.Format("   Year:         {0}", myCal.GetYear(myDT)) & vbCrLf
      outputBlock.Text += String.Format("   Month:        {0}", myCal.GetMonth(myDT)) & vbCrLf
      outputBlock.Text += String.Format("   DayOfYear:    {0}", myCal.GetDayOfYear(myDT)) & vbCrLf
      outputBlock.Text += String.Format("   DayOfMonth:   {0}", myCal.GetDayOfMonth(myDT)) & vbCrLf
      outputBlock.Text += String.Format("   DayOfWeek:    {0}", myCal.GetDayOfWeek(myDT)) & vbCrLf
      outputBlock.Text += String.Format("   Hour:         {0}", myCal.GetHour(myDT)) & vbCrLf
      outputBlock.Text += String.Format("   Minute:       {0}", myCal.GetMinute(myDT)) & vbCrLf
      outputBlock.Text += String.Format("   Second:       {0}", myCal.GetSecond(myDT)) & vbCrLf
      outputBlock.Text += String.Format("   Milliseconds: {0}", myCal.GetMilliseconds(myDT)) & vbCrLf
      outputBlock.Text &= vbCrLf
   End Sub 
End Class  
' This example produces the following output.
'       April 3, 2002 of the Gregorian calendar:
'          Era:          1
'          Year:         2002
'          Month:        4
'          DayOfYear:    93
'          DayOfMonth:   3
'          DayOfWeek:    Wednesday
'          Hour:         0
'          Minute:       0
'          Second:       0
'          Milliseconds: 0
'       
'       After adding 5 to each component of the DateTime:
'          Era:          1
'          Year:         2007
'          Month:        10
'          DayOfYear:    286
'          DayOfMonth:   13
'          DayOfWeek:    Saturday
'          Hour:         5
'          Minute:       5
'          Second:       5
'          Milliseconds: 5


Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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