C# Date Time Parser

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Introduction

Once I needed to detect and recognize date and/or time contained in internet messages. Those messages were sent by different users, and so could not comply with certain format. They consisted usually of 1 or 2 sentences and it was impossible to foresee where a date and/or time is within them. Thus, built-in .NET method DateTime.Parse() could not help because this method can parse only strings consisting exactly of a date/time presentation, it cannot look for date/time among text. Moreover, some yet prevalent date presentations appeared to not be recognized by DateTime.Parse().

What I needed was a C# function like the universal Perl's str2time() or PHP's strtotime(). After some Googling, I was surprised not to find such a code in C#. That's why I wrote a date/time parsing class presented here.

Description

The class DateTimeRoutines exposes several date/time parsing methods. The general idea is finding first instance of the date and/or time within a string and converting it into DateTime.

These methods accept DateTimeFormat parameter that specifies a recognition format used as preferred in ambivalent instances.

These methods return a ParsedDateTime object. This object describes whether a date (or time) was found within the string and where it was found (if it was), and also hosts a DateTime structure as a result of parsing.

Also, these methods have derivations that return a DateTime directly instead of ParsedDateTime. The use of the origin methods is preferable though because their output allows knowing whether a date (or time) was really found or if it was set by default value.

Notice that TryParseDateTime() and TryParseTime() may return different times in the case where a string contains more than one time. TryParseDateTime() looks for a time around a date, while TryParseTime() returns a time that was found first.

Local and Absolute Time

ParsedDateTime.DateTime is always considered local meaning that it reflects the parsed string literally. If UTC offset or time zone abbreviation indicating that the time is absolute was found in the time string then ParsedDateTime.IsUtcOffsetFound is true and ParsedDateTime.UtcDateTime is UTC date&time. If ParsedDateTime.IsUtcOffsetFound is false, then ParsedDateTime.UtcDateTime should be disregarded as undefined.

Notice that TryParseDate() does not detect time zone

Usage

The date formats that can be recognized by DateTimeRoutines can be seen in the test strings listed below (the complete list of parsed formats can be found in Test project supplied with the code):

@"Member since:      10-Feb-2008"
@"Last Update: 18:16 11 Feb '08 "
@"date    Tue, Feb 10, 2008 at 11:06 AM"
@"see at 12/31/2007 14:16:32"
@"sack finish 14:16:32 November 15 2008, 1-144 app"
@"Genesis Message - Wed 04 Feb 08 - 19:40"
@"The day 07/31/07 14:16:32 is "
@"Shipping is on us until December 24, 2008 within the U.S." 
@" 2008 within the U.S. at 14:16:32"
@"5th November, 1994, 8:15:30 pm"
@"7 boxes January 31 , 14:16:32."
@"the blue sky of Sept  30th  2008 14:16:32"
@" e.g. 1997-07-16T19:20:30+01:00"
@"Apr 1st, 2008 14:16:32 tufa 6767"
@"wait for 07/31/07 14:16:32"
@"later 12.31.08 and before 1.01.09"
@"Expires: Sept  30th  2008 14:16:32"
@"Offer expires Apr 1st, 2007, 14:16:32"
@"Expires  14:16:32 January 31."
@"Expires  14:16:32 January 31-st."
@"Expires 23rd January 2010."
@"Expires January 22nd, 2010."
@"Expires DEC 22, 2010."

A code sample if you need to get only date:

string str = @"The last round was June 10, 2005; this time the unbroken record was held.";
DateTimeRoutines.ParsedDateTime pdt;
if (DateTimeRoutines.TryParseDate(str, DateTimeRoutines.DateTimeFormat.USA_DATE, out pdt))
    Console.WriteLine("Date was found: " + pdt.DateTime.ToString());

A code sample if you want to get date and, if possible, time:

string str = @"The last round was June 10, 2005; this time the unbroken record was held.";
DateTimeRoutines.ParsedDateTime pdt;
if (DateTimeRoutines.TryParse(str, DateTimeRoutines.DateTimeFormat.USA_DATE, out pdt)
    && pdt.IsDateFound
    )
    Console.WriteLine("Date was found: " + pdt.DateTime.ToString());

A code sample if you want to get only completely specified date and time:

string str = @"The last round was June 10, 2005 10:30AM; this time the unbroken record was held.";
DateTimeRoutines.ParsedDateTime pdt;
if(str.TryParseDateTime(DateTimeRoutines.DateTimeFormat.USA_DATE, out pdt))
    Console.WriteLine("Date&time was found: " + pdt.DateTime.ToString());

A code sample if you want to get UTC date and time:

string str = @"Your program recognizes string : 21 Jun 2010 04:20:19 -0430 blah blah.";
DateTimeRoutines.ParsedDateTime pdt;
if(str.TryParseDateTime(DateTimeRoutines.DateTimeFormat.USA_DATE, out pdt) && pdt.IsUtcOffsetFound) 
Console.WriteLine("UTC date&time was found: " + pdt.UtcDateTime.ToString());

.NET Version Consistency

DateTimeRoutines is formed as a .NET 4 DLL that exposes the parsing methods as extensions for string class. The DLL can be called by .NET 2 code just as well. However, if you want to embed DateTimeRoutines source code into your .NET 2 project, you'll have to remove keyword this from the method parameters.

Conclusion

This code satisfied my needs. I did not want to implement too wide a recognition capability like say, the one provided by Perl's str2time(), because more wide recognition capability results in a higher error rate when the parser tries to detect a date/time within any part of a string.

Nevertheless, DateTimeRoutines is capable of recognizing the formats that usually are used in a correspondence. If you find some prevalent date/time format which is not recognized, please let me know and I'll update the code.

The Code

In the attached code, you can find the DateTimeRoutines project containing:

• A class DateTimeRoutines that is compiled as a DLL
• Project Test

The code is licensed as public domain code.

The latest version can be found on SourceForge.

Be happy!

History

• 11^th February, 2009
  • Initial post
• 14^th February, 2009
  • TryParseDateTime() added
• 18^th December, 2009
  • TryParseDate() updated
• 3^rd March, 2010
  • TryParseDate() updated
• 12^th March, 2010
  • locks removed
• 13^th March, 2010
  • Formed as a DLL
  • Methods formed as extensions for string class
  • TryParse() renamed to TryParseDateOrTime()
• 13^th July, 2010
  • Updated source code
• 15^th May, 2011
  • Fixed 12pm and 12am
  • Upgraded to C# 4.0
• 18^th April, 2012
  • Added one more date format
• 28^th June, 2012
  • Added UTC recognition;