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

If you want to RoundUp or RoundDown ... like Ceil and Floor...

Here there are (do not forget to add Math unit to your uses clause):

function RoundUpToNearest(TheDateTime,TheRoundStep:TDateTime):TDateTime;
    begin
         if 0=TheRoundStep
         then begin // If round step is zero there is no round at all
                   RoundUpToNearest:=TheDateTime;
              end
         else begin // Just round up to nearest bigger or equal multiple of TheRoundStep
                   RoundUpToNearest:=Ceil(TheDateTime/TheRoundStep)*TheRoundStep;
              end;
    end;

function RoundDownToNearest(TheDateTime,TheRoundStep:TDateTime):TDateTime;
    begin
         if 0=TheRoundStep
         then begin // If round step is zero there is no round at all
                   RoundDownToNearest:=TheDateTime;
              end
         else begin // Just round down to nearest lower or equal multiple of TheRoundStep
                   RoundDownToNearest:=Floor(TheDateTime/TheRoundStep)*TheRoundStep;
              end;
    end;

And of course with a minor change (use Float type instead of TDateTime type) if can also be used to Round, RoundUp and RoundDown decimal/float values to a decimal/float step.

Here they are:

function RoundUpToNearest(TheValue,TheRoundStep:Float):Float;
    begin
         if 0=TheRoundStep
         then begin // If round step is zero there is no round at all
                   RoundUpToNearest:=TheValue;
              end
         else begin // Just round up to nearest bigger or equal multiple of TheRoundStep
                   RoundUpToNearest:=Ceil(TheValue/TheRoundStep)*TheRoundStep;
              end;
    end;

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

function RoundDownToNearest(TheValue,TheRoundStep:Float):Float;
    begin
         if 0=TheRoundStep
         then begin // If round step is zero there is no round at all
                   RoundDownToNearest:=TheDateTime;
              end
         else begin // Just round down to nearest lower or equal multiple of TheRoundStep
                   RoundDownToNearest:=Floor(TheValue/TheRoundStep)*TheRoundStep;
              end;
    end;

If you want to use both types (TDateTime and Float) on same unit... add overload directive on interface section, example:

function RoundUpToNearest(TheDateTime,TheRoundStep:TDateTime):TDateTime;overload;
function RoundToNearest(TheDateTime,TheRoundStep:TDateTime):TDateTime;overload;
function RoundDownToNearest(TheDateTime,TheRoundStep:TDateTime):TDateTime;overload;

function RoundUpToNearest(TheValue,TheRoundStep:Float):Float;overload;
function RoundToNearest(TheValue,TheRoundStep:Float):Float;overload;
function RoundDownToNearest(TheValue,TheRoundStep:Float):Float;overload;