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SameTime

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

Example​

procedure ScriptEvent(var Value: variant);
var
  FirstDay, SecondDay: TDateTime;
begin
  FirstDay := EncodeDateTime(2026, 7, 16, 8, 30, 15, 125);
  SecondDay := EncodeDateTime(2027, 1, 5, 8, 30, 15, 125);
  Value := SameTime(FirstDay, SecondDay); // True
end;

Usage​

SameTime reports whether two values have the same millisecond-normalised time of day, ignoring their dates.

Parameters

NameTypeDescription
ATDateTime, constFirst value whose time portion is compared.
BTDateTime, constSecond value whose time portion is compared.

Returns

True when both values produce the same rounded millisecond-of-day count; otherwise False.

Behaviour

  • Calendar dates are ignored completely.
  • Comparison includes milliseconds but discards smaller floating differences through rounding.
  • Abs(Frac(...)) makes ordinary valid pre-epoch time portions compare correctly with the same post-epoch clock fields.
  • The comparison is symmetric and timezone-neutral.

Errors

Valid finite values do not normally raise. Velox does not add validation or exception handling.

Usage notes

Use TimeOf when the raw time fraction is required. Use SameDateTime when both date and time must match.

Additional Technical Info​

SameTime compares only the time-of-day portions of two values after reducing them to integer milliseconds. Their calendar dates are ignored.

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

Implementation

The DateUtils import binds directly to Delphi 37.0 System.DateUtils.SameTime. It calls the internal TimeToMilliSeconds helper for both arguments. That helper obtains TimeOf using raw Frac, takes its absolute value, multiplies by 86,400,000 and rounds to the nearest integer before comparison.

Edge cases and quirks

  • SameTime does not compare raw fractions. Values with slightly different binary representations can be equal after nearest-millisecond rounding.
  • Arbitrary raw fractions extremely close to the next day can round to 86,400,000. Properly encoded Delphi values normally resolve no later than 23:59:59.999.
  • The function does not establish simultaneous instants or account for timezone offsets.
  • TimeOf itself returns a negative raw fraction for timed pre-epoch values; SameTime deliberately applies Abs inside its helper.
  • Free Pascal documents the public result through CompareTime; installed Delphi uses the explicit rounded millisecond helper above.

Side effects

None.

Performance and concurrency

Constant-time fractional arithmetic and integer comparison with no I/O or shared mutable state.

Related entries

  • TimeOf exposes the raw fractional part.
  • SameDateTime includes the encoded calendar date.

External references

Created 2026-07-15