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WithinPastDays

Function WithinPastDays( const ANow, AThen : TDateTime; const ADays : Integer) : Boolean

Example​

procedure ScriptEvent(var Value: variant);
var
  FirstValue, SecondValue: TDateTime;
begin
  FirstValue := EncodeDateTime(2026, 4, 1, 0, 0, 0, 0);
  SecondValue := EncodeDateTime(2026, 4, 3, 23, 59, 59, 999);
  Value := WithinPastDays(FirstValue, SecondValue, 2);
  // Value is True: the complete-day distance is 2.
end;

Usage​

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

Parameters

NameTypeDescription
ANowTDateTimeOne encoded date/time endpoint; parameter order is immaterial.
AThenTDateTimeThe other encoded date/time endpoint.
ADaysIntegerInclusive maximum number of complete days. A negative limit cannot match a non-negative distance.

Returns

True when DaysBetween(ANow, AThen) <= ADays; otherwise False.

Behaviour

Fractional days are discarded before comparison. Consequently, a distance of 2 days 23:59:59.999 is considered within 2 days, while exactly 3 days is not. The inputs are rounded to encoded millisecond resolution by DateTimeToTimeStamp.

Important usage notes

  • The predicate is symmetric: future and past directions are treated identically.
  • It measures fixed 24-hour encoded days, not changes of calendar date and not timezone-aware civil days.
  • A negative ADays returns False, including when both endpoints are equal, because the computed distance is never negative.
  • Valid pre-1899 dates are timestamp-normalised and retain chronological ordering.

Errors

Velox adds no exception handling. Arithmetic or conversion failures for values outside the representable TDateTime range propagate.

Additional Technical Info​

Reports whether the absolute distance between ANow and AThen, measured in complete encoded days, is less than or equal to ADays. Despite its name, it does not require either value to be in the past or compare them with the current clock.

Implementation

Velox binds directly to System.DateUtils.WithinPastDays. The terminal is a single inclusive comparison against DaysBetween. That helper converts both values to millisecond timestamps, takes the absolute difference and performs integer division by 86,400,000.

Performance and concurrency

The routine is constant-time integer arithmetic and reads no host clock or shared Velox state.

Related entries

  • DaysBetween — returns the complete-day value compared by this predicate.
  • WithinPastHours — applies the same rule in complete hours.
  • DaySpan — returns a fractional raw day span with different pre-epoch behaviour.

External references

Created 2026-07-15