checking of correct datetime format is not working

Question

User-1355965324 posted

Hi

I want to check the given string value is correct  format for converting into  datetime  variable before to convert into date time variable.  But the value '05/03/2020 8:15:00' is showed as incorrect format . Please can you advise me where is the problem

eg: datetimestring  ='05/03/2020 8:15:00'

                string clockeddate = log.AttendanceDate;
                string timeclock = log.Hrs + ':' + log.Mins;
                string datetimestring = clockeddate + " " + timeclock+":00";

                DateTime dDate;
                bool isCorrectDateFormat =   DateTime.TryParseExact(datetimestring, "dd/MM/yyyy HH:mm:ss",
                    CultureInfo.InvariantCulture, DateTimeStyles.None, out dDate);
                if(isCorrectDateFormat)
                {
                     dDate = Convert.ToDateTime(clockeddate + " " + timeclock);
                }

Answer 1

User753101303 posted

Hi,

HH requires two digits. Try H instead. I tend to use TryParse especially with the invariant culture.

Edit: for example

using System;
using System.Globalization;
					
public class Program
{
   public static void Main()
   {
      DateTime dDate;
      foreach(string value in new string[] {"05/03/2020 8:15:00", "05/03/2020 08:15:00" })
      {
         Console.WriteLine(DateTime.TryParseExact(value, "dd/MM/yyyy HH:mm:ss", CultureInfo.InvariantCulture, DateTimeStyles.None, out dDate));
         Console.WriteLine(DateTime.TryParseExact(value, "dd/MM/yyyy H:mm:ss", CultureInfo.InvariantCulture, DateTimeStyles.None, out dDate));
         Console.WriteLine(DateTime.TryParse(value,CultureInfo.InvariantCulture,DateTimeStyles.None, out dDate));
      }
   }
}

shows False for the very first result and True otherwise.

Answer 2

User-1716253493 posted

Hi Polacan,

I assume that you have AttendanceDate in DateTime type, Hrs, Mins in double or integer.

So, why you make a datetime string to get dDate?

 You can calculate the values directly without convert it to a string first.

https://docs.microsoft.com/en-us/dotnet/api/system.datetime.addhours?view=netframework-4.8

Answer 3

User-854763662 posted

Hi polachan ,

As PatriceSc said , you make the mistake on the Date Format . The "H" custom format specifier represents the hour as a number from 0 through 23; that is, the hour is represented by a zero-based 24-hour clock that counts the hours since midnight. A single-digit hour is formatted without a leading zero. 

 The "HH" custom format specifier (plus any number of additional "H" specifiers) represents the hour as a number from 00 through 23; that is, the hour is represented by a zero-based 24-hour clock that counts the hours since midnight. A single-digit hour is formatted with a leading zero.

Refer to  Custom date and time format strings for more details.

Best Regards,

Sherry