格式化带偏移量的日期

Question

我正在尝试使用 Offset 更改字符串 DateTime 值。这是我尝试过的过程，但最后， datetime 和 datetime1 都打印了它们的初始值。我想要的输出是将 datetime1 格式化为正确的偏移量，以便它反映 datetime

01/10/2016 5:18 PM
01/10/2016 5:18 PM-05:00

string datetime = "2017-01-10T17:18:00-05:00";
string datetime1 = "1/10/2016 3:18:00 PM";

DateTimeOffset dateTimeOffset = DateTimeOffset.Parse(datetime);
TimeSpan tspan = dateTimeOffset.Offset;
DateTimeOffset alteredDate = new     DateTimeOffset(Convert.ToDateTime(datetime1)).ToOffset(tspan);

UAB = Convert.ToString(DateTimeOffset.Parse(alteredDate.ToString()));

Console.WriteLine(datetime);
Console.WriteLine(UAB);
Console.ReadLine();

编辑
在单步执行我的代码时，我注意到 tpsan 的值为 -05:00 可能 - 符号是导致代码无法正确转换的原因吗？

Answer 1

使用不同的构造函数：

DateTimeOffset alteredDate = 
    new DateTimeOffset( Convert.ToDateTime( datetime1 ), tspan );

这是文档：

//
// Summary:
//     Initializes a new instance of the System.DateTimeOffset structure using the specified
//     System.DateTime value and offset.
//
// Parameters:
//   dateTime:
//     A date and time.
//
//   offset:
//     The time's offset from Coordinated Universal Time (UTC).
//
// Exceptions:
//   T:System.ArgumentException:
//     dateTime.Kind equals System.DateTimeKind.Utc and offset does not equal zero.-or-dateTime.Kind
//     equals System.DateTimeKind.Local and offset does not equal the offset of the
//     system's local time zone.-or-offset is not specified in whole minutes.
//
//   T:System.ArgumentOutOfRangeException:
//     offset is less than -14 hours or greater than 14 hours.-or-System.DateTimeOffset.UtcDateTime
//     is less than System.DateTimeOffset.MinValue or greater than System.DateTimeOffset.MaxValue.
public DateTimeOffset(DateTime dateTime, TimeSpan offset);

Answer 2

您收到的 DateTimeOffset 对象已经针对时区进行了调整。

string output = "";

// Parsing with explicit timezones
var withZeroOffset = DateTimeOffset.Parse("2017-01-10T17:18:00-00:00"); // parsed as UTC
var withOffset = DateTimeOffset.Parse("2017-01-10T17:18:00-05:00"); // Parsed as specific timezone
var withoutOffset = DateTimeOffset.Parse("2017-01-10T17:18:00"); // Parsed as my timezone
output += "All Times:\n" + withZeroOffset + "\n" + withOffset + "\n" + withoutOffset + "\n\n";

// Modifying timezones
var inputUtc = DateTimeOffset.Parse("2017-01-10T17:18:00Z").ToOffset(TimeSpan.Zero);
output += "Time UTC: " + inputUtc + "\n";
var minusFive = inputUtc.ToOffset(TimeSpan.FromHours(-5));
output += "Time @ -5:00: " + minusFive + "\n";
var myOffset = TimeZone.CurrentTimeZone.GetUtcOffset(DateTime.Now);
var myTime = inputUtc.ToOffset(myOffset);
output += "Time in my timezone: (" + myOffset.TotalHours + ":00): " + myTime + "\n";

Console.WriteLine(output);

在我的机器上，使用我的时区，我得到这个输出：

All Times:
1/10/2017 5:18:00 PM +00:00
1/10/2017 5:18:00 PM -05:00
1/10/2017 5:18:00 PM -08:00

Time UTC: 1/11/2017 1:18:00 AM +00:00
Time @ -5:00: 1/10/2017 8:18:00 PM -05:00
Time in my timezone: (-8:00): 1/10/2017 5:18:00 PM -08:00

我假设您的显式偏移与您的实际时区相匹配，这就是您两次看到相同答案的原因。要显式更改 DateTimeOffset 对象的时区，请使用 .ToOffset()。

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