How to truncate milliseconds off of a NET DateTime

Question

I m trying to compare a time stamp from an incoming request to a database stored value  SQL Server of course keeps some precision of milliseconds on the time  and when read into a  NET DateTime  it includes those milliseconds  The incoming request to the system  however  does not offer that precision  so I need to simply drop the milliseconds   I feel like I m missing something obvious  but I haven t found an elegant way to do it  C

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var date   DateTime Now   date   new DateTime date Year  date Month  date Day  date Hour  date Minute  date Second  date Kind

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I know the answer is quite late  but the best way to get rid of milliseconds is  var currentDateTime   DateTime Now ToString  s      Try printing the value of the variable  it will show the date time  without milliseconds

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A way for easy reading is       Remove milliseconds DateTime date   DateTime Now  date   DateTime ParseExact date ToString  yyyy-MM-dd HH mm ss     yyyy-MM-dd HH mm ss   null     And more       Remove seconds DateTime date   DateTime Now  date   DateTime ParseExact date ToString  yyyy-MM-dd HH mm     yyyy-MM-dd HH mm   null      Remove minutes DateTime date   DateTime Now  date   DateTime ParseExact date ToString  yyyy-MM-dd HH     yyyy-MM-dd HH   null      and go on

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DateID Text   DateTime Today ToShortDateString     Use ToShortDateString     Date 2-02-2016 Use ToShortDateString      Time    And By Use Of   ToLongDateString      its show 19 February 2016     P

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The following will work for a DateTime that has fractional milliseconds  and also preserves the Kind property  Local  Utc or Undefined    DateTime dateTime       anything     dateTime   new DateTime      dateTime Ticks -  dateTime Ticks   TimeSpan TicksPerSecond        dateTime Kind          or the equivalent and shorter   dateTime   dateTime AddTicks  -  dateTime Ticks   TimeSpan TicksPerSecond      This could be generalized into an extension method   public static DateTime Truncate this DateTime dateTime  TimeSpan timeSpan        if  timeSpan    TimeSpan Zero  return dateTime     Or could throw an ArgumentException     if  dateTime    DateTime MinValue    dateTime    DateTime MaxValue  return dateTime     do not modify  guard  values     return dateTime AddTicks - dateTime Ticks   timeSpan Ticks        which is used as follows   dateTime   dateTime Truncate TimeSpan FromMilliseconds 1       Truncate to whole ms dateTime   dateTime Truncate TimeSpan FromSeconds 1       Truncate to whole second dateTime   dateTime Truncate TimeSpan FromMinutes 1       Truncate to whole minute

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This is my version of the extension methods posted here and in similar questions  This validates the ticks value in an easy to read way and preserves the DateTimeKind of the original DateTime instance   This has subtle but relevant side effects when storing to a database like MongoDB    If the true goal is to truncate a DateTime to a specified value  i e  Hours Minutes Seconds MS  I recommend implementing this extension method in your code instead  It ensures that you can only truncate to a valid precision and it preserves the important DateTimeKind metadata of your original instance   public static DateTime Truncate this DateTime dateTime  long ticks        bool isValid   ticks    TimeSpan TicksPerDay             ticks    TimeSpan TicksPerHour             ticks    TimeSpan TicksPerMinute             ticks    TimeSpan TicksPerSecond             ticks    TimeSpan TicksPerMillisecond          https   stackoverflow com questions 21704604 have-datetime-now-return-to-the-nearest-second     return isValid            DateTime SpecifyKind              new DateTime                  dateTime Ticks -  dateTime Ticks   ticks                             dateTime Kind                     throw new ArgumentException  Invalid ticks value given  Only TimeSpan tick values are allowed         Then you can use the method like this   DateTime dateTime   DateTime UtcNow Truncate TimeSpan TicksPerMillisecond    dateTime Kind   gt  DateTimeKind Utc

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Less obvious but more than 2 times faster       10000000 runs  DateTime d   DateTime Now      484 375ms d   new DateTime  d Ticks   TimeSpan TicksPerSecond    TimeSpan TicksPerSecond       1296 875ms d   d AddMilliseconds -d Millisecond

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Sometimes you want to truncate to something calendar-based  like year or month  Here s an extension method that lets you choose any resolution   public enum DateTimeResolution       Year  Month  Day  Hour  Minute  Second  Millisecond  Tick    public static DateTime Truncate this DateTime self  DateTimeResolution resolution   DateTimeResolution Second        switch  resolution                case DateTimeResolution Year              return new DateTime self Year  1  1  0  0  0  0  self Kind           case DateTimeResolution Month              return new DateTime self Year  self Month  1  0  0  0  self Kind           case DateTimeResolution Day              return new DateTime self Year  self Month  self Day  0  0  0  self Kind           case DateTimeResolution Hour              return self AddTicks - self Ticks   TimeSpan TicksPerHour            case DateTimeResolution Minute              return self AddTicks - self Ticks   TimeSpan TicksPerMinute            case DateTimeResolution Second              return self AddTicks - self Ticks   TimeSpan TicksPerSecond            case DateTimeResolution Millisecond              return self AddTicks - self Ticks   TimeSpan TicksPerMillisecond            case DateTimeResolution Tick              return self AddTicks 0           default              throw new ArgumentException  unrecognized resolution    resolution

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Instead of dropping the milliseconds then comparing  why not compare the difference   DateTime x  DateTime y  bool areEqual    x-y  TotalSeconds    0    or  TimeSpan precision   TimeSpan FromSeconds 1   bool areEqual    x-y  Duration    lt  precision

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2 Extension methods for the solutions mentioned above      public static bool LiesAfterIgnoringMilliseconds this DateTime theDate  DateTime compareDate  DateTimeKind kind                DateTime thisDate   new DateTime theDate Year  theDate Month  theDate Day  theDate Hour  theDate Minute  theDate Second  kind           compareDate   new DateTime compareDate Year  compareDate Month  compareDate Day  compareDate Hour  compareDate Minute  compareDate Second  kind            return thisDate  gt  compareDate              public static bool LiesAfterOrEqualsIgnoringMilliseconds this DateTime theDate  DateTime compareDate  DateTimeKind kind                DateTime thisDate   new DateTime theDate Year  theDate Month  theDate Day  theDate Hour  theDate Minute  theDate Second  kind           compareDate   new DateTime compareDate Year  compareDate Month  compareDate Day  compareDate Hour  compareDate Minute  compareDate Second  kind            return thisDate  gt   compareDate          usage   bool liesAfter   myObject DateProperty LiesAfterOrEqualsIgnoringMilliseconds startDateTime  DateTimeKind Utc

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DateTime d   DateTime Now  d   d AddMilliseconds -d Millisecond

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Not the fastest solution but simple and easy to understand   DateTime d   DateTime Now  d   d Date AddHours d Hour  AddMinutes d Minute  AddSeconds d Second

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To round down to the second   dateTime AddTicks -dateTime Ticks   TimeSpan TicksPerSecond    Replace with TicksPerMinute to round down to the minute     If your code is performance sensitive  be cautious about   new DateTime date Year  date Month  date Day  date Hour  date Minute  date Second    My app was spending 12  of CPU time in System DateTime GetDatePart

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New Method   String Date   DateTime Today ToString  dd-MMM-yyyy          define String pass parameter dd-mmm-yyyy  return 24-feb-2016    Or shown on textbox   txtDate Text   DateTime Today ToString  dd-MMM-yyyy         put on PageonLoad

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Here is an extension method based on a previous answer that will let you truncate to any resolution     Usage   DateTime myDateSansMilliseconds   myDate Truncate TimeSpan TicksPerSecond   DateTime myDateSansSeconds   myDate Truncate TimeSpan TicksPerMinute    Class   public static class DateTimeUtils            lt summary gt           lt para gt Truncates a DateTime to a specified resolution  lt  para gt           lt para gt A convenient source for resolution is TimeSpan TicksPerXXXX constants  lt  para gt           lt  summary gt           lt param name  date  gt The DateTime object to truncate lt  param gt           lt param name  resolution  gt e g  to round to nearest second  TimeSpan TicksPerSecond lt  param gt           lt returns gt Truncated DateTime lt  returns gt      public static DateTime Truncate this DateTime date  long resolution                return new DateTime date Ticks -  date Ticks   resolution   date Kind

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Regarding Diadistis response  This worked for me  except I had to use Floor to remove the fractional part of the division before the multiplication  So   d   new DateTime  d Ticks   TimeSpan TicksPerSecond    TimeSpan TicksPerSecond     becomes  d   new DateTime Math Floor d Ticks   TimeSpan TicksPerSecond    TimeSpan TicksPerSecond     I would have expected the division of two Long values to result in a Long  thus removing the decimal part  but it resolves it as a Double leaving the exact same value after the multiplication   Eppsy

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In my case  I was aiming to save TimeSpan from datetimePicker tool without saving the seconds and the milliseconds  and here is the solution   First convert the datetimePicker value to your desired format  which mine is  HH mm  then convert it back to TimeSpan   var datetime   datetimepicker1 Value ToString  HH mm    TimeSpan timeSpan   Convert ToDateTime datetime  TimeOfDay

[c#] How to truncate milliseconds off of a .NET DateTime

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