问题
I'm modifying a globalized web application which uses stored CultureInfo for each logged in user.
The client would like time data entry to be localized. Displaying is not a problem as the formatting is already available. However I need to detect if the current cultureinfo is for 24 hour time or am/pm so I can display the correct input boxes (not just a textfield).
My initial idea was to check the DateTimeInfo property of CultureInfo and see if the ShortTimePattern contained a capital H or a lower case h but this didn't feel robust enough for me.
Is there a better way? I've read the class properties of both but unless I'm missing something, I can't see any existing methods or properties.
回答1:
I don't think there is a better way to obtain that information. The time pattern for a culture could contain anything (a user could even create a custom culture where the ShortTimePattern is "\hello" and then DateTime.ToString() would return "hello" for any time). In that case how could the framework determine if that CultureInfo is in 24-hour or 12-hour format?
So a "normal" DateTimeFormatInfo.ShortTimePattern will necessarily contain either a 'h' or a 'H', otherwise the hour will not be displayed. I think you can follow your initial idea and check for that. You can also check that the 'h' or 'H' is not escaped with a \ like in my "\hello" example because that would not represent the hour :)
回答2:
The most robust way is to check if DateTimeFormatInfo.AMDesignator is an empty string.
if (DateTimeFormatInfo.CurrentInfo.AMDesignator == "")
//24hour format
else
//12hour format
回答3:
Checking for 'H'/'h' seems more robust than checking for the AM/PM Designator. A good example is en-gb: The time format string is HH:mm and the AM/PM designators are set to AM/PM Windows will display the time in 24h format! This seems to be an inconsistent definition but checking for 'H' fixed my bug.
来源：https://stackoverflow.com/questions/1134985/cultureinfo-datetimeinfo-how-to-check-if-is-24-hour-time