How to convert string offset to timespan in c#

Question

I'm trying to convert the convert time to the user's time zone, but I don't have the windows time zone string such as "Pacific Standard Time". All I have is a string offset such as "-07:00". Looks like I need to create a timespan. Is the only way to parse this string manually?. Seems like there should be a way to convert a time using a string offset, but maybe I am missing something.

I have this but it requires the timezone. I'm trying to modify it to use the offset instead, but you can see the timespan that is created for the conversion and I need to get my offset to the timespan.

static void Main(string[] args)
{
    var currentTimeInPacificTime = ConvertUtcTimeToTimeZone(DateTime.UtcNow, "Pacific Standard Time");
    //TimeSpan ts = new TimeSpan("-07:00");
    Console.ReadKey();
}

static DateTimeOffset ConvertUtcTimeToTimeZone(DateTime dateTime, string toTimeZoneDesc)
{
    if (dateTime.Kind != DateTimeKind.Utc) throw new Exception("dateTime needs to have Kind property set to Utc");
    TimeSpan toUtcOffset = TimeZoneInfo.FindSystemTimeZoneById(toTimeZoneDesc).GetUtcOffset(dateTime);
    var convertedTime = DateTime.SpecifyKind(dateTime.Add(toUtcOffset), DateTimeKind.Unspecified);
    return new DateTimeOffset(convertedTime, toUtcOffset);
}

Answer 1

You can just use the TimeSpan.Parse method:

TimeSpan ts = TimeSpan.Parse("-07:00");
Console.WriteLine(ts);   // -07:00:00

Be careful to strip a leading "+" as TimeSpan.Parse will fail here. "+01:00" is incorrect, but "01:00" works.

Or if you want be a little more safe, try the TimeSpan.TryParse method:

TimeSpan ts;
if (TimeSpan.TryParse("-07:00", out ts))
    Console.WriteLine(ts);   // -07:00:00

But of course if all you want to do is convert a UTC date/time to a local date/time, you can just do this:

DateTime localDateTime = utcDateTime.ToLocalTime();

Or to convert it to any timezone:

TimeZoneInfo tzi = TimeZoneInfo.FindSystemTimeZoneById(toTimeZoneDesc);
DateTime localDateTime = TimeZoneInfo.ConvertTime(utcDateTime, tzi);

Answer 2

For more complicated/non-standard formats you can also use TimeSpan.ParseExact(String, String, IFormatProvider), where the second String is a Custom TimeSpan Format String.

API information is available at msdn.microsoft.com, and is linked above.linked.