问题
I have a Time Value stored as string with the format HH:mm
I used the following code to parse it as date with Today Date
DateTime.ParseExact("09:00","HH:mm",New System.Globalization.CultureInfi("En-GB"))
The Result Is 2017-03-15 09:00:00
When Running this Code From another machine i get the following Result: 1899-12-31 09:00:00
I replaced my code to the following
DateTime.ParseExact(DateTime.Now.ToString("yyyy-MM-dd") & " 09:00","yyyy-MM-dd HH:mm",New System.Globalization.CultureInfi("En-GB"))
And it works Fine, But i still want to Know why every system parsed the date to a different Value???
回答1:
Default values for missing Year/Month/Day in DateTime.ParseExact
From .NET source code:
The following table describes the behaviors of getting the default value
when a certain year/month/day values are missing.
An "X" means that the value exists. And "--" means that value is missing.
Year Month Day => ResultYear ResultMonth ResultDay Note
X X X Parsed year Parsed month Parsed day
X X -- Parsed Year Parsed month First day If we have year and month, assume the first day of that month.
X -- X Parsed year First month Parsed day If the month is missing, assume first month of that year.
X -- -- Parsed year First month First day If we have only the year, assume the first day of that year.
-- X X CurrentYear Parsed month Parsed day If the year is missing, assume the current year.
-- X -- CurrentYear Parsed month First day If we have only a month value, assume the current year and current day.
-- -- X CurrentYear First month Parsed day If we have only a day value, assume current year and first month.
-- -- -- CurrentYear Current month Current day So this means that if the date string only contains time, you will get current date.
来源：https://stackoverflow.com/questions/42802362/time-parsing-issue-using-datetime-parseexact