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DateTime.ToUniversalTime Method

Updated: January 2010

Converts the value of the current DateTime object to Coordinated Universal Time (UTC).

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

public function ToUniversalTime() : DateTime

Return Value

Type: System.DateTime
A DateTime object whose Kind property is Utc, and whose value is the UTC equivalent to the value of the current DateTime object, or MaxValue if the converted value is too large to be represented by a DateTime object, or MinValue if the converted value is too small to be represented by a DateTime object.

The Coordinated Universal Time (UTC) is equal to the local time minus the UTC offset. For more information about the UTC offset, see TimeZone.GetUtcOffset. The conversion also takes into account the daylight saving time rule that applies to the time represented by the current DateTime object.

Important noteImportant Note:

   The ToUniversalTime method recognizes only the current adjustment rule when converting from local time to UTC. As a result, conversions for periods before the current adjustment rule came into effect may not accurately reflect the difference between local time and UTC.

Starting with the .NET Framework version 2.0, the value returned by the ToUniversalTime method is determined by the Kind property of the current DateTime object. The following table describes the possible results.

Kind

Results

Utc

No conversion is performed.

Local

The current DateTime object is converted to UTC.

Unspecified

The current DateTime object is assumed to be a local time, and the conversion is performed as if Kind were Local.

NoteNote:

The ToUniversalTime method converts a DateTime value from local time to UTC. To convert the time in a non-local time zone to UTC, use the TimeZoneInfo.ConvertTimeToUtc(DateTime, TimeZoneInfo) method. To convert a time whose offset from UTC is known, use the ToUniversalTime method.

If the date and time instance value is an ambiguous time, this method assumes that it is a standard time. (An ambiguous time is one that can map either to a standard time or to a daylight saving time in the local time zone) If the date and time instance value is an invalid time, this method simply subtracts the local time from the local time zone's UTC offset to return UTC. (An invalid time is one that does not exist because of the application of daylight saving time adjustment rules.)

Notes to Callers:

The ToUniversalTime method is sometimes used to convert a local time to UTC, and subsequently to restore it by calling the ToLocalTime method. However, if the original time represents an invalid time in the local time zone, the two local time values will not be equal. For additional information and an example, see the ToLocalTime method.

The following example demonstrates the ToUniversalTime method.

No code example is currently available or this language may not be supported.

The following example uses the SpecifyKind method to demonstrate how the Kind property influences the ToLocalTime and ToUniversalTime conversion methods.

No code example is currently available or this language may not be supported.

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, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

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, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

Date

History

Reason

January 2010

Added the Notes for Callers section.

Content bug fix.

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