Zoned dateTime to UTC Time - LocalDateTimePattern throws exception - timezone

Question

I am trying to obtain the UTC time from a zoned datetime using LocalDateTime pattern in NodaTime using the below code.
public string getUtcTimeFromZonedTime(string dateTimeString, string timeZoneID,
string dateTimePattern, bool isDateTime)
{
if (string.IsNullOrEmpty(dateTimePattern))
{
if (isDateTime)
{
dateTimePattern = "M/dd/yyyy HH:mm:ss tt";
}
else
{
dateTimePattern = "M/dd/yyyy";
}
}
var pattern = LocalDateTimePattern.CreateWithInvariantCulture(dateTimePattern);
var parseResult = pattern.Parse(dateTimeString);
if (!parseResult.Success)
{
// throw an exception or whatever you want to do
}
var localDateTime = parseResult.Value;
var timeZone = DateTimeZoneProviders.Tzdb[timeZoneID];
// TODO: Consider how you want to handle ambiguous or "skipped" local date/time
// values. For example, you might want InZoneStrictly, or provide your own custom
// handler to InZone.
var zonedDateTime = localDateTime.InZoneLeniently(timeZone);
return zonedDateTime.ToDateTimeUtc().ToString();
}
I get an exception during Parsing during below mentioned scenarios-
1) If pattern is like "MM/dd/yyyy HH:mm:ss tt" and the DateTime string is something like "5/28/2013 1:02:ss PM"
2) If pattern is like "MM-dd-yyyy HH:mm:ss tt" and the DateTime string is something like "5/28/2013 1:02:ss PM"
For the first case, it will work if I change my pattern to "M/dd/yyyy HH:mm:ss tt", but i will end up losing the leading zero. Second case will work if I change the pattern to "MM/dd/yyyy HH:mm:ss tt"
Is there any alternative way for getting the UTC values or am I doing something wrong over here.

Answer 1

1) If pattern is like "MM/dd/yyyy HH:mm:ss tt" and the DateTime string is something like "5/28/2013 1:02:ss PM"
Yes, because you've specified that you'll give it a two-digit hour, and you've only given one digit. Note that if you're using an AM/PM designator, you probably want h rather than H anyway.
2) If pattern is like "MM-dd-yyyy HH:mm:ss tt" and the DateTime string is something like "5/28/2013 1:02:ss PM"
Yes, because you've specified that you want - as the separator, but you're using / in the text.
I suspect you want:
dateTimePattern = "M/dd/yyyy h:mm:ss tt";
Note that this has nothing to do with converting to UTC - it's just the parsing to LocalDateTime that's causing you problems.