In Delphi: How do I round a TDateTime to closest second, minute, five-minute etc?

Question

Does there exist a routine in Delphi that rounds a TDateTime value to the closest second, closest hour, closest 5-minute, closest half hour etc?

UPDATE:

Gab

Answer 1

Wow! guys, how do you complicate too much something so simple... also most of you loose the option to round to nearest 1/100 second, etc...

This one is much more simple and can also round to milisenconds parts:

function RoundToNearest(TheDateTime,TheRoundStep:TDateTime):TdateTime;
    begin
         if 0=TheRoundStep
         then begin // If round step is zero there is no round at all
                   RoundToNearest:=TheDateTime;
              end
         else begin // Just round to nearest multiple of TheRoundStep
                   RoundToNearest:=Round(TheDateTime/TheRoundStep)*TheRoundStep;
              end;
    end;

You can just test it with this common or not so common examples:

// Note: Scroll to bottom to see examples of round to 1/10 of a second, etc

// Round to nearest multiple of one hour and a half (round to 90'=1h30')
ShowMessage(FormatDateTime('hh:nn:ss.zzz'
                          ,RoundToNearest(EncodeTime(15,31,37,156)
                                         ,EncodeTime(1,30,0,0))
                          )
           );

// Round to nearest multiple of one hour and a quarter (round to 75'=1h15')
ShowMessage(FormatDateTime('hh:nn:ss.zzz'
                          ,RoundToNearest(EncodeTime(15,31,37,156)
                                         ,EncodeTime(1,15,0,0))
                          )
           );

// Round to nearest multiple of 60 minutes (round to hours)
ShowMessage(FormatDateTime('hh:nn:ss.zzz'
                          ,RoundToNearest(EncodeTime(15,31,37,156)
                                         ,EncodeTime(1,0,0,0))
                          )
           );

// Round to nearest multiple of 60 seconds (round to minutes)
ShowMessage(FormatDateTime('hh:nn:ss.zzz'
                          ,RoundToNearest(EncodeTime(15,31,37,156)
                                         ,EncodeTime(0,1,0,0))
                          )
           );

// Round to nearest multiple of second (round to seconds)
ShowMessage(FormatDateTime('hh:nn:ss.zzz'
                          ,RoundToNearest(EncodeTime(15,31,37,156)
                                         ,EncodeTime(0,0,1,0))
                          )
           );

// Round to nearest multiple of 1/100 seconds
ShowMessage(FormatDateTime('hh:nn:ss.zzz'
                          ,RoundToNearest(EncodeTime(15,31,37,141)
                                         ,EncodeTime(0,0,0,100))
                          )
           );

// Round to nearest multiple of 1/100 seconds
    ShowMessage(FormatDateTime('hh:nn:ss.zzz'
                          ,RoundToNearest(EncodeTime(15,31,37,156)
                                         ,EncodeTime(0,0,0,100))
                          )
           );

// Round to nearest multiple of 1/10 seconds
    ShowMessage(FormatDateTime('hh:nn:ss.zzz'
                          ,RoundToNearest(EncodeTime(15,31,37,151)
                                         ,EncodeTime(0,0,0,10))
                          )
           );

// Round to nearest multiple of 1/10 seconds
    ShowMessage(FormatDateTime('hh:nn:ss.zzz'
                          ,RoundToNearest(EncodeTime(15,31,37,156)
                                         ,EncodeTime(0,0,0,10))
                          )
           );

Hope this helps people like me, that need to round to 1/100, 1/25 or 1/10 seconds.