Parsing Dates and Times in .NET

Parsing Dates and Times in .NET<H1>Parsing Dates and Times in .NET</H1> Parsing dates and times using DateTime.Parse and DateTime.ParseExact is simple enough once you know how they work. It’s simple if you know the format of the string you’re getting and it exactly matches one of the built-in formats, or if you’re willing to let the framework do it’s best to parse the string and you’re ok with it failing otherwise, but if you need to parse specific formats, you’ll need to build your own format specifiers. There are two ways of parsing date strings:  Parse and ParseExact DateTime.Parse() is the simplest.  It tries to figure out the format of the date, and usually does a pretty good job.  Here are some examples that work for me, with the result of a DateTime.ToString() on the parsed date: <TABLE cellSpacing=0 cellPadding=0 border=1> <TBODY> <TR> <TD vAlign=top width=295> String to parse<?xml:namespace prefix = o /><o:p></o:p></TD> <TD vAlign=top width=295 .5pt? windowtext solid mso-border-left-alt: .5pt; -border-alt: 0in; -BOTTOM:> Resulting DateTime.ToString<o:p></o:p></TD></TR> <TR style="mso-yfti-irow: 1"> <TD vAlign=top width=295> 01-Jan-2005</TD> <TD vAlign=top width=295> 1/1/2005 12:00:00 AM</TD></TR> <TR style="mso-yfti-irow: 2"> <TD vAlign=top width=295> 01-Jan-2005 12:34 PM</TD> <TD vAlign=top width=295> 1/1/2005 12:34:00 PM</TD></TR> <TR style="mso-yfti-irow: 3"> <TD vAlign=top width=295> 1/1/05 1:3</TD> <TD vAlign=top width=295> 1/1/2004 1:03:00 AM</TD></TR> <TR style="mso-yfti-irow: 4"> <TD vAlign=top width=295> 1 march, 2005 1 am</TD> <TD vAlign=top width=295> 3/1/2005 1:00:00 AM</TD></TR> <TR style="mso-yfti-irow: 5"> <TD vAlign=top width=295> 1995-02-04</TD> <TD vAlign=top width=295> 2/4/1995 12:00:00 AM</TD></TR> <TR> <TD vAlign=top width=295> February 3</TD> <TD vAlign=top width=295> 2/3/2005 12:00:00 AM</TD></TR> <TR> <TD vAlign=top width=295> 10:30</TD> <TD vAlign=top width=295> 2/15/2005 10:30:00 AM</TD></TR> <TR> <TD vAlign=top width=295> 10 am</TD> <TD vAlign=top width=295> 2/15/2005 10:00:00 AM</TD></TR></TBODY></TABLE> These all did what we expected. DateTime.Parse() is probably the best function to use if the user is typing in a date, and you want it parsed so you can work with it.  If you’re receiving your date strings from data (network, etc), and they’re in a specific format, check this table to see if there’s a predefined format string for your format:<o:p> <TABLE cellSpacing=0 cellPadding=0 border=1> <TBODY> <TR style="mso-yfti-irow: 0; mso-yfti-firstrow: yes"> <TD vAlign=top width=143> Standard</TD> <TD vAlign=top width=61> Format</TD> <TD vAlign=top width=288> Example Date</TD></TR> <TR style="mso-yfti-irow: 1"> <TD vAlign=top width=143> RFC1123</TD> <TD vAlign=top width=61 windowtext 0in; mso transparent; BACKGROUND-COLOR: solid; 1pt BORDER-BOTTOM: PADDING-TOP: 45.5pt; WIDTH: #ece9d8; BORDER-LEFT:> r</TD> <TD vAlign=top width=288 windowtext 0in; mso transparent; BACKGROUND-COLOR: solid; 1pt BORDER-BOTTOM: PADDING-TOP: WIDTH: #ece9d8; BORDER-LEFT: 216.25pt;><PRE>Sun, 06 Nov 1994 08:49:37 GMT</PRE></TD></TR> <TR style="mso-yfti-irow: 2"> <TD vAlign=top width=143 windowtext 0in; BACKGROUND-COLOR: solid; 1pt BORDER-BOTTOM: PADDING-TOP: WIDTH: BORDER-LEFT: tr 107.55pt;> ISO 8601 (almost)</TD> <TD vAlign=top width=61 windowtext 0in; mso transparent; BACKGROUND-COLOR: solid; 1pt BORDER-BOTTOM: PADDING-TOP: 45.5pt; WIDTH: #ece9d8; BORDER-LEFT:> s</TD> <TD vAlign=top width=288 windowtext 0in; mso transparent; BACKGROUND-COLOR: solid; 1pt BORDER-BOTTOM: PADDING-TOP: WIDTH: #ece9d8; BORDER-LEFT: 216.25pt;> 1993-02-14T13:10:30<o:p></o:p></TD></TR> <TR style="mso-yfti-irow: 3; mso-yfti-lastrow: yes"> <TD vAlign=top width=143 windowtext 0in; BACKGROUND-COLOR: solid; 1pt BORDER-BOTTOM: PADDING-TOP: WIDTH: BORDER-LEFT: tr 107.55pt;> Universal Sortable</TD> <TD vAlign=top width=61 windowtext 0in; mso transparent; BACKGROUND-COLOR: solid; 1pt BORDER-BOTTOM: PADDING-TOP: 45.5pt; WIDTH: #ece9d8; BORDER-LEFT:> u</TD> <TD vAlign=top width=288 windowtext 0in; mso transparent; BACKGROUND-COLOR: solid; 1pt BORDER-BOTTOM: PADDING-TOP: WIDTH: #ece9d8; BORDER-LEFT: 216.25pt;> 2004-04-30 04:30:00Z<o:p></o:p></TD></TR></TBODY></TABLE> <o:p> </o:p></o:p>If there is, then you can use ParseExact with the single-character format specifier like this:             // Parse an RFC1123 date             DateTime dt = DateTime.ParseExact(dateString, “r”); There are other strings you can pass to ParseExact, but they’re culture-specific, so generally not all that useful. In many cases, you have a date string in a specific format,which doesn’t just work with DateTime.Parse.  One example is this one, which is allowed by the the <A href="http://hydracen.com/dx/iso8601.htm">ISO 8601</A> standard, but not parsed by ParseExact when you specify the ‘s’ specifier:             19930214T131030 To parse this, you need to build a string that specifies the format you’re expecting, using characters from this table: <TABLE cellSpacing=0 cellPadding=0 border=1> <TBODY> <TR> <TD vAlign=top> Format specifier<o:p></o:p></TD> <TD vAlign=top> Description<o:p></o:p></TD></TR> <TR> <TD vAlign=top> d, dd, ddd, dddd</TD> <TD vAlign=top BACKGROUND-COLOR: BORDER-BOTTOM: PADDING-TOP: WIDTH: #ece9d8; transparent? 0.75pt; 75%; LEFT:> Current day of the month  d, dd=numeric, ddd=abbreviation (ie, ‘Wed’), dddd=spelled out.</TD></TR> <TR style="mso-yfti-irow: 2"> <TD vAlign=top> f, ff, fff, ffff, fffff, …</TD> <TD vAlign=top> Fractions of a second, varying numbers of digits</TD></TR> <TR style="mso-yfti-irow: 3"> <TD vAlign=top> h, hh</TD> <TD vAlign=top> Hours, 12 hour format. </TD></TR> <TR style="mso-yfti-irow: 4"> <TD vAlign=top> H, HH</TD> <TD vAlign=top> Hours, 24 hour format</TD></TR> <TR style="mso-yfti-irow: 5"> <TD vAlign=top> m, mm</TD> <TD vAlign=top> Minutes</TD></TR> <TR> <TD vAlign=top> M, MM, MMM, MMMM</TD> <TD vAlign=top> Month.  MM = 2 digit, MMM = abbreviation (ie, ‘Jan’), MMMM=Spelled out.</TD></TR> <TR style="mso-yfti-irow: 7"> <TD vAlign=top> s, ss</TD> <TD vAlign=top> Seconds</TD></TR> <TR style="mso-yfti-irow: 8"> <TD vAlign=top> t, tt</TD> <TD vAlign=top> AM/PM indicator. </TD></TR> <TR style="mso-yfti-irow: 9"> <TD vAlign=top> y, yy, yyyy</TD> <TD vAlign=top> Year</TD></TR> <TR style="mso-yfti-irow: 10"> <TD vAlign=top> z, zz, zzz</TD> <TD vAlign=top> Time zone offset from GMT. </TD></TR> <TR style="mso-yfti-irow: 11"> <TD vAlign=top> :</TD> <TD vAlign=top> Time separator.</TD></TR> <TR style="mso-yfti-irow: 12"> <TD vAlign=top> /</TD> <TD vAlign=top> Date separator.</TD></TR> <TR style="mso-yfti-irow: 13; mso-yfti-lastrow: yes"> <TD vAlign=top> Any other character </TD> <TD vAlign=top> Other characters are matched as literals.</TD></TR></TBODY></TABLE> <o:p> </o:p>So to parse our sample date, you’d use this string:       // Parse an RFC1123 date       DateTime dt = DateTime.ParseExact(“19930214T131030”, “yyyyMMddTHHmmss”);<o:p></o:p> The help covers this stuff fairly well, once you find the documentation.  Look for ‘<A href="http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpconstandarddatetimeformatstrings.asp">Standard DateTime Format Strings</A>’ and ‘<A href="http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpconcustomdatetimeformatstrings.asp">Custom DateTime Format Strings</A>’ if you haven’t found what you need here (and let me know, so I can add it). If you’re receiving strings in a number of formats and you’re not really sure what you’re going to get (like, say, if you’re writing a program that does something with RSS feed data), it’s convenient that you can pass in multiple format specifiers to ParseExact.  For example: string[] formats = new string[] { “r”, “s”, “u”, “yyyyMMddTHHmmss” };       DateTime dt = DateTime.ParseExact(dateString, formats, CultureInfo.InvariantCulture, DateTimeStyles.AdjustToUniversal);<o:p></o:p> This is most likely to get you a date you can use.  Thu, 01 Sep 2005 19:17:08 GMT