TimeZoneInfo.IsAmbiguousTime Method (DateTime)
[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
Determines whether a particular date and time in a particular time zone is ambiguous and can be mapped to two or more Coordinated Universal Time (UTC) times.
Assembly: mscorlib (in mscorlib.dll)
Parameters
- dateTime
- Type: System.DateTime
A date and time value.
| Exception | Condition |
|---|---|
| ArgumentException | The Kind property of the dateTime value is DateTimeKind.Local and dateTime is an invalid time. |
An ambiguous time falls within a range of times for the current time zone. This means it can be either a standard time or a time that results from the application of an adjustment rule. Typically, ambiguous times result when the clock is set to return to standard time from daylight saving time. See the Example section for an illustration.
Coordinated Universal Time (UTC) has no ambiguous times; neither do time zones that do not support daylight saving time. Therefore, these time zones have no adjustment rules and calls to the IsAmbiguousTime method always return false.
For time zones that do observe daylight saving time, the precise behavior of this method depends on the relationship between the Kind property and the TimeZoneInfo object, as the following table shows.
TimeZoneInfo object type | Kind property value | Behavior |
|---|---|---|
Determines whether the dateTime parameter is ambiguous. | ||
Converts dateTime to the local time and then determines whether that time is ambiguous. | ||
Returns false. | ||
If dateTime is ambiguous, assumes it is a standard time, converts it to UTC, and returns false. | ||
Any other time zone. | Converts dateTime to the time in the specified time zone and then determines whether that time is ambiguous. | |
Any other time zone. | Determines whether dateTime is ambiguous. |
Version Notes
XNA Framework
When this method is used in the XNA Framework, it throws a NotSupportedException exception.In the Pacific Standard Time zone, which is the local time zone on the computer on which this example runs, daylight saving time ends at 2:00 A.M. on November 4, 2007. The following example passes the time at one-minute intervals from 12:59 A.M. on November 4, 2007, to 2:01 A.M. on November 4, 2007, to the IsAmbiguousTime(DateTime) method of a TimeZoneInfo object that represents the Pacific Standard Time zone. The console output indicates that all times from 1:00 A.M. on November 4, 2007, to 1:59 A.M. on November 4, 2007, are ambiguous.
// Specify DateTimeKind in Date constructor. DateTime baseTime = new DateTime(2007, 11, 4, 0, 59, 00, DateTimeKind.Unspecified); DateTime newTime; // List possible ambiguous times for 63-minute interval, from 12:59 AM to 2:01 AM. // This assumes the local time zone is U.S. Pacific Standard Time. for (int ctr = 0; ctr < 63; ctr++) { // Because of assignment, newTime.Kind is also DateTimeKind.Unspecified. newTime = baseTime.AddMinutes(ctr); outputBlock.Text += String.Format("{0} is ambiguous: {1}", newTime, TimeZoneInfo.Local.IsAmbiguousTime(newTime)) + "\n"; }