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WithinPastHours

Function WithinPastHours( const ANow, AThen : TDateTime; const AHours : Int64) : Boolean

Example​

procedure ScriptEvent(var Value: variant);
var
  FirstValue, SecondValue: TDateTime;
begin
  FirstValue := EncodeDateTime(2026, 4, 1, 9, 0, 0, 0);
  SecondValue := EncodeDateTime(2026, 4, 1, 11, 59, 59, 999);
  Value := WithinPastHours(FirstValue, SecondValue, 2);
  // Value is True: the complete-hour distance is 2.
end;

Usage​

WithinPastHours reports whether two date/time values are no more than a supplied number of complete hours apart.

Parameters

NameTypeDescription
ANowTDateTimeOne endpoint; it need not represent the later value or the actual current time.
AThenTDateTimeThe other encoded endpoint.
AHoursInt64Inclusive complete-hour limit. Negative limits produce False.

Returns

True when HoursBetween(ANow, AThen) <= AHours; otherwise False.

Behaviour

The fractional part of an hour is discarded before the inclusive comparison. A distance of 2 hours 59 minutes therefore passes a limit of 2; exactly 3 hours does not.

Important usage notes

  • Parameter order and temporal direction are ignored because the distance is absolute.
  • Hours are fixed 60-minute encoded durations. No timezone or daylight-saving rules are applied.
  • Timestamp conversion rounds the original Double values to milliseconds.
  • A negative limit returns False even for identical endpoints.

Errors

No Velox function catches failures. Invalid or non-representable encoded inputs can propagate RTL arithmetic or conversion errors.

Additional Technical Info​

Reports whether two encoded date/time values are no more than AHours complete hours apart. The calculation is an absolute duration test, not a directional "past" test.

Implementation

Velox binds directly to System.DateUtils.WithinPastHours. The installed function calls HoursBetween, whose terminal converts both inputs to millisecond timestamps, takes their absolute difference and divides it by 3,600,000 using integer division.

Performance and concurrency

The routine performs fixed integer arithmetic, allocates no objects and reads no host or Velox shared state.

Related entries

  • HoursBetween — returns the complete-hour distance used here.
  • WithinPastMinutes — applies the same comparison in complete minutes.
  • HourSpan — returns a fractional raw span rather than a floored timestamp distance.

External references

Created 2026-07-15