如何将字符串转换为日期时间

Question

 string value =     "Sat Apr 28 2012 11:00:00 GMT-0400 (Eastern Daylight Time)"

I need to convert to date time

I tried doing:

 DateTime datetime = DateTime.ParseExact(value, "MM/dd/yyyy hh:mm", null);

or

 DateTime datetime2 = Convert.ToDateTime(value);

Exception: String was not recognized as a valid DateTime.

Answer 1

You're specifying a format of `MM/dd/yyyy hh:mm" but your string isn't in that format even slightly .

I suspect you'll have trouble with the "GMT-0400 (Eastern Daylight Time)" part - the rest is in a format of "ddd MMM dd yyyy HH:mm:ss" or "ddd MMM d yyyy HH:mm:ss" if the day-of-month number isn't always two digits.

I suggest you parse the offset from UTC separately, and create a DateTimeOffset - parse the first part (before GMT) as an unspecified DateTime - and then parse the offset. EDIT: You can parse the offset with TimeSpan.ParseExact but you'll need to handle the sign yourself, I believe - I can't see any documented way of parsing a negative timespan that way :(

EDIT: Note that my Noda Time project would allow you to parse the offset part, eg with a pattern of "'GMT'+HHmm" - and obviously we'd cope with the LocalDateTime part - but you'd still need to separate the different parts of the string from each other. Sample code:

using System;
using System.Linq;
using System.Xml.Linq;
using NodaTime;
using NodaTime.Text;

public class Test
{
    static void Main()
    {
        string text = "Sat Apr 28 2012 11:00:00 GMT-0400 (Eastern Daylight Time)";
        ZonedDateTime parsed = Parse(text);
        Console.WriteLine(parsed);
    }

    static readonly LocalDateTimePattern LocalPattern =
        LocalDateTimePattern.CreateWithInvariantInfo("ddd MMM d yyyy HH:mm:ss");

    // Note: Includes space before GMT for convenience later
    static readonly OffsetPattern OffsetPattern =
        OffsetPattern.CreateWithInvariantInfo("' GMT'+HHmm");

    static ZonedDateTime Parse(string text)
    {
        int gmtIndex = text.IndexOf(" GMT");
        int zoneIndex = text.IndexOf(" (");
        // TODO: Validation that these aren't -1 :)

        string localText = text.Substring(0, gmtIndex);
        string offsetText = text.Substring(gmtIndex, zoneIndex - gmtIndex);

        var localResult = LocalPattern.Parse(localText);
        var offsetResult = OffsetPattern.Parse(offsetText);

        // TODO: Validate that both are successful

        var fixedZone = DateTimeZone.ForOffset(offsetResult.Value);        
        return localResult.Value.InZoneStrictly(fixedZone);
    }
}

Note that this will give a ZonedDateTime in a fixed time zone - not really Eastern time. Currently Noda Time doesn't have an OffsetDateTime , which would be a natural fit here...

Answer 2

请尝试以下操作：

Convert.ToDateTime("Sat Apr 28 2012 11:00:00 GMT-0400 (Eastern Daylight Time)".Substring(4, 20))

Answer 3

Your string doesn't match your format.

You need to parse that string a bit before trying to convert it. For example, "Apr 28 2012 11:00:00" could be parsed. But, you'll need to convert the rest of it yourself.

You may want to look into using DateTimeOffset documented here , because it can hold time relative to UTC, like your string.

Found this is the documentation, pretty close to what you have

// Parse date and time with custom specifier.
dateString = "Sun 15 Jun 2008 8:30 AM -06:00";
format = "ddd dd MMM yyyy h:mm tt zzz";
try
{
    result = DateTimeOffset.ParseExact(dateString, format, provider);
    Console.WriteLine("{0} converts to {1}.", dateString, result.ToString());
}
catch (FormatException)
{
   Console.WriteLine("{0} is not in the correct format.", dateString);
} 

Answer 4

try ddd MMM d yyyy hh:mm:ss zzz

If it's not working try this

Answer 5

If you have a look at the Custom Date and Time Format Strings , what you have is just a variant of this format:

"ddd MMM dd yyyy h:mm:ss zzz"

Only there are some extra pieces in it:

"ddd MMM dd yyyy h:mm:ss GMTzzz (blah blah blah)"

If you deal with those, you should be fine:

value = value.Remove(value.IndexOf(" ("));
DateTime datetime = DateTime.ParseExact(value, "ddd MMM dd yyyy hh:mm:ss \"GMT\"zzz", null);