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TimeOf

Function TimeOf( const AValue : TDateTime) : TDateTime

Example​

procedure ScriptEvent(var Value: variant);
var
  InputValue: TDateTime;
begin
  InputValue := EncodeDateTime(2026, 7, 16, 14, 30, 0, 0);
  Value := TimeOf(InputValue); // Same fraction as EncodeTime(14, 30, 0, 0)
end;

Usage​

TimeOf returns the raw fractional-day portion of a TDateTime value.

Parameters

NameTypeDescription
AValueTDateTime, constEncoded value whose raw fractional portion is required.

Returns

Frac(AValue) as a TDateTime. Its magnitude represents time of day; its sign follows the raw input.

Behaviour

  • For zero or positive values, the result is normally in the half-open range 0 to less than 1.
  • Calendar whole days are discarded.
  • Floating precision is preserved; the result is not quantised to milliseconds by this routine.
  • No clock, timezone or locale state is used.

Errors

No validation is performed. Ordinary finite values do not raise; core floating behaviour applies to invalid raw values.

Usage notes

Use component extractors such as HourOf when sign-independent clock fields are wanted. Avoid using raw TimeOf subtraction for pre-epoch chronology.

Additional Technical Info​

TimeOf returns the raw fractional portion of the Double-backed TDateTime. For ordinary post-epoch values this is the familiar non-negative fraction of a day.

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.TimeOf. The complete installed implementation is Result := Frac(AValue); it performs no decoding, absolute-value operation, validation or rounding.

Edge cases and quirks

  • Delphi encodes a timed pre-epoch date using a negative fractional part. TimeOf therefore returns a negative result for such a value, even though its magnitude represents a positive time after midnight.
  • This is why SameTime applies Abs(TimeOf(...)) before rounding to milliseconds.
  • If a universally non-negative time fraction is required, the caller must account for the pre-epoch sign deliberately; do not silently use raw subtraction.
  • Arbitrary non-finite Double values are outside the valid date/time contract.
  • Free Pascal provides the same-name operation, but dialect representation details should not be used to override installed Delphi behaviour.

Side effects

None.

Performance and concurrency

Constant-time floating-point Frac operation with no I/O or shared state.

Related entries

  • SameTime compares absolute rounded time portions.
  • HourOf decodes a sign-independent hour component.

External references

Created 2026-07-15