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HourOfTheDay

Function HourOfTheDay(const AValue: TDateTime): Word

Example​

procedure ScriptEvent(var Value: variant);
begin
  Value := HourOfTheDay(EncodeTime(23, 59, 59, 999)); // 23
end;

Usage​

HourOfTheDay returns the zero-based hour elapsed within the encoded day as an exact alias of HourOf.

Parameters

NameTypeDescription
AValueTDateTime, constEncoded date/time whose hour-of-day component is returned.

Returns

A Word in 0..23. Fractions within the current hour are discarded because the result is the hour field, not a fractional duration.

Important usage notes

  • Despite the “hours since start of day” wording sometimes used for this family, this entry is exactly the 24-hour clock component.
  • It does not round: 00:59:59.999 returns 0.
  • It reads no timezone and does not distinguish UTC from local values.
  • All valid pre-epoch behaviour is identical to HourOf.

Errors

Unsupported raw values can fail in DecodeTime; no handler is present.

Additional Technical Info​

HourOfTheDay returns the complete zero-based hour within a day. In the installed Delphi implementation it is an inline alias of HourOf, so both functions have the same result and edge behaviour.

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.HourOfTheDay. The RTL implementation delegates exactly to HourOf(AValue), which calls DecodeTime and returns its hour output.

Side effects

None.

Performance and concurrency

Constant-time extraction with no allocation or shared state.

Related entries

External references

Created 2026-07-15