格式化日期时间C＃

Question

I just wanted to change one string of date to DateTime.

However when I try to print, it always said that the result is 5/31/2009 8:00:00 AM

Any idea why this thing happens?

namespace Test
{
    class Test
    {
        static void Main()
        {
            Parse("5/31/2009 12:00:00 AM" );
        }

        static readonly string ShortFormat = "M/d/yyyy hh:mm:ss tt";

        static readonly string[] Formats = { ShortFormat };

        static void Parse(string text)
        {
            // Adjust styles as per requirements
            DateTime result = DateTime.ParseExact(text, ShortFormat,
                                                  CultureInfo.InvariantCulture,
                                                  DateTimeStyles.AssumeUniversal);
            Console.WriteLine(result);
            Console.WriteLine(result);
        }
    }
}

Answer 1

You need to use DateTimeStyles.None or DateTimeStyles.AssumeLocal if you want the DateTime parsed to not take account of timezones:

DateTime result = DateTime.ParseExact(text, ShortFormat,
                                      CultureInfo.InvariantCulture,
                                      DateTimeStyles.None);

When you use DateTimeStyles.AssumeUniversal an automatic timezone conversion occurs against the computer timezone.

See the documentation :

AssumeUniversal - If no time zone is specified in the parsed string, the string is assumed to denote a UTC.

Answer 2

我想你需要写日期格式的MM/dd/yyyy hh:mm:ss tt 。

Answer 3

In order to print a DateTime in a specified format you need to use the ToString method. Like so.

result.ToString("M/d/yyyy hh:mm:ss tt");

The second parameter ( format ) defines the format that the string ( S ) must be in for it to be parsed.

Answer 4

All the DateTime formats are described here and here . You should instead use

static readonly string ShortFormat = "MM/dd/yyyy hh:mm:ss tt";

Answer 5

Change shortformat to

static readonly string ShortFormat = "MM/dd/yyyy hh:mm:ss tt";

Your string stand for this

"05/31/2009 12:00:00 AM"
"MM/dd/yyyy hh:mm:ss tt"

Number on top corresponds to format below

Answer 6

It depends on your time zone, and I think your time zone is GMT+4 not GMT-4 as bukko answered. Anyway, just use:

DateTimeStyles.AssumeLocal

instead of:

DateTimeStyles.AssumeUniversal