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SameDate

Function SameDate( const A, B : TDateTime) : Boolean

Example​

procedure ScriptEvent(var Value: variant);
var
  MorningValue, EveningValue: TDateTime;
begin
  MorningValue := EncodeDateTime(2026, 7, 16, 8, 0, 0, 0);
  EveningValue := EncodeDateTime(2026, 7, 16, 18, 30, 0, 0);
  Value := SameDate(MorningValue, EveningValue); // True
end;

Usage​

SameDate reports whether two TDateTime values have the same truncated encoded date portion.

Parameters

NameTypeDescription
ATDateTime, constFirst encoded value.
BTDateTime, constSecond encoded value.

Returns

True when Trunc(A) equals Trunc(B); otherwise False.

Behaviour

  • Any two ordinary times on the same encoded calendar date compare equal.
  • The comparison is symmetric.
  • Timezone, daylight-saving and locale information are not present in either value and are not considered.
  • Valid pre-epoch values use Velox's negative TDateTime representation; truncation still selects their encoded date integer.

Errors

Ordinary finite TDateTime inputs do not raise. Velox performs no additional validation.

Usage notes

Use SameDateTime when date and millisecond-resolved time must both match. Use SameTime when only the time of day matters.

Additional Technical Info​

SameDate reports whether two encoded values have the same date portion. Their time-of-day fields are deliberately ignored.

The example is fictional, deterministic and source-reviewed. It was not executed by the documentation workflow.

Implementation

The DateUtils script import binds directly to Delphi 37.0 System.DateUtils.SameDate. The installed implementation applies Trunc to both Double-backed TDateTime values and compares the integer results. It does not call SameDateTime, decode individual fields or consult a tolerance.

Edge cases and quirks

  • This is a raw date-part comparison. It does not determine whether two timezone-aware instants fall on the same local date.
  • No validation or normalisation occurs before Trunc. Arbitrary non-finite or out-of-range floating values are outside the normal TDateTime contract.
  • IsSameDay is a different routine: it tests whether one raw value falls within an interval based on another and has a documented timed pre-epoch defect. SameDate compares two truncated date parts directly.
  • Free Pascal currently describes its implementation through CompareDate; that is compatible at the API level but is not the terminal used by installed Delphi.

Side effects

None.

Performance and concurrency

Constant-time floating-point truncation and integer comparison with no allocation, I/O or shared state.

Related entries

  • SameDateTime compares date and time down to the encoded millisecond.
  • IsSameDay has different value/basis interval semantics.

External references

Created 2026-07-15