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EastAsianLunisolarCalendar.AddMonths Method

Updated: February 2009

Calculates the date that is the specified number of months away from the specified date.

Namespace:  System.Globalization
Assembly:  mscorlib (in mscorlib.dll)

public override DateTime AddMonths(
	DateTime time,
	int months


Type: System.DateTime

The DateTime to which to add months.

Type: System.Int32

The number of months to add.

Return Value

Type: System.DateTime
A new DateTime that results from adding the specified number of months to the time parameter.


The result is outside the supported range of a DateTime.


months is less than -120000 or greater than 120000.


time is less than MinSupportedDateTime or greater than MaxSupportedDateTime.

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. In this case, the day part 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. This implementation supports only the current era. Therefore, ArgumentException is thrown 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, if the specified month is October, which has 31 days, the specified day is the thirty-first 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 April, and the resulting day is the thirtieth day, which is the last day in April.

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);

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5, 3.0, 2.0




February 2009

Added information about the Kind property.

Content bug fix.