Check if a string is a valid date using DateTime TryParse

Question

I am using DateTime TryParse   function to check if a particular string is a valid datetime not depending on any cultures   To my surprise   the function returns true for even strings like  1-1    1 1   etc   How can I solve this problem   Update   Does it mean  if I want to check if a particular string is valid datetime  I need a huge array of formats    There will be different combinations   I believe  Even there are lots of date separator                -   etc    depending on the culture  it will be difficult for me to define an array of format to check against    Basically  I want to check if a particular string contains  AT LEAST  day 1 through 31 or 01 through 31  month 1 through 12 or 01 through 12  and year yyyy or yy  in any order  with any date separator   what will be the solution   So  if the value includes any parts of time  it should return true too  I could NOT be able to define a array of format

User · Accepted Answer

If you want your dates to conform a particular format or formats then use DateTime.TryParseExact otherwise that is the default behaviour of DateTime.TryParse

DateTime.TryParse

This method tries to ignore unrecognized data, if possible, and fills in missing month, day, and year information with the current date. If s contains only a date and no time, this method assumes the time is 12:00 midnight. If s includes a date component with a two-digit year, it is converted to a year in the current culture's current calendar based on the value of the Calendar.TwoDigitYearMax property. Any leading, inner, or trailing white space character in s is ignored.

If you want to confirm against multiple formats then look at DateTime.TryParseExact Method (String, String[], IFormatProvider, DateTimeStyles, DateTime) overload. Example from the same link:

string[] formats= {"M/d/yyyy h:mm:ss tt", "M/d/yyyy h:mm tt", 
                   "MM/dd/yyyy hh:mm:ss", "M/d/yyyy h:mm:ss", 
                   "M/d/yyyy hh:mm tt", "M/d/yyyy hh tt", 
                   "M/d/yyyy h:mm", "M/d/yyyy h:mm", 
                   "MM/dd/yyyy hh:mm", "M/dd/yyyy hh:mm"};
string[] dateStrings = {"5/1/2009 6:32 PM", "05/01/2009 6:32:05 PM", 
                        "5/1/2009 6:32:00", "05/01/2009 06:32", 
                        "05/01/2009 06:32:00 PM", "05/01/2009 06:32:00"}; 
DateTime dateValue;

foreach (string dateString in dateStrings)
{
   if (DateTime.TryParseExact(dateString, formats, 
                              new CultureInfo("en-US"), 
                              DateTimeStyles.None, 
                              out dateValue))
      Console.WriteLine("Converted '{0}' to {1}.", dateString, dateValue);
   else
      Console.WriteLine("Unable to convert '{0}' to a date.", dateString);
}
// The example displays the following output: 
//       Converted '5/1/2009 6:32 PM' to 5/1/2009 6:32:00 PM. 
//       Converted '05/01/2009 6:32:05 PM' to 5/1/2009 6:32:05 PM. 
//       Converted '5/1/2009 6:32:00' to 5/1/2009 6:32:00 AM. 
//       Converted '05/01/2009 06:32' to 5/1/2009 6:32:00 AM. 
//       Converted '05/01/2009 06:32:00 PM' to 5/1/2009 6:32:00 PM. 
//       Converted '05/01/2009 06:32:00' to 5/1/2009 6:32:00 AM.

User · Answer

TestCase  11 08 1995   Result  true    TestCase  1-1   Result   false    TestCase  1 1   Result   false   public bool IsValidDateTimeTest string dateTime        string   formats      MM dd yyyy         DateTime parsedDateTime      return DateTime TryParseExact dateTime  formats  new CultureInfo  en-US                                       DateTimeStyles None  out parsedDateTime       Simply  specify the date time formats that you wish to accept in the array named formats

User · Answer

Basically  I want to check if a particular string contains AT LEAST day 1 through 31 or 01 through 31  month 1 through 12 or 01 through 12  and year yyyy or yy  in any order  with any date separator   what will be the solution     So  if the value includes any parts of time  it should return true too  I could NOT be able to define a array of format    When I was in a similar situation  here is what I did    Gather all the formats my system is expected to support  Looked at what is common or can be generalize  Learned to create REGEX  It is an investment of time initially but pays off once you create one or two on your own   Also do not try to build REGEX for all formats in one go  follow incremental process  I created REGEX to cover as many format as possible  For few cases  not to make REGEX extra complex  I covered it through DateTime Parse   method  With the combination of both Parse as well as REGEX i was able to validate the input is correct as expected    This http   www codeproject com Articles 13255 Validation-with-Regular-Expressions-Made-Simple was really helpful both for understanding as well as validation the syntax for each format   My 2 cents if it helps

User · Answer

Use  DateTime TryParseExact   if you want to match against a specific date format    string format    ddd dd MMM h mm tt yyyy   DateTime dateTime  if  DateTime TryParseExact dateString  format  CultureInfo InvariantCulture      DateTimeStyles None  out dateTime         Console WriteLine dateTime     else       Console WriteLine  Not a date

User · Answer

So this question has been answered but to me the code used is not simple enough or complete  To me this bit here is what I was looking for and possibly some other people will like this as well   string dateString    198101    if  DateTime TryParse dateString  out DateTime Temp     true           do stuff     The output is stored in Temp and not needed afterwards  datestring is the input string to be tested

User · Answer

Try using  DateTime ParseExact      txtPaymentSummaryBeginDate Text Trim         MM dd yyyy        System Globalization CultureInfo InvariantCulture      It throws an exception if the input string is not in proper format  so in the catch section you can return false

[c#] Check if a string is a valid date using DateTime.TryParse

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