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HourOfTheYear

Function HourOfTheYear(const AValue: TDateTime): Word

Example​

procedure ScriptEvent(var Value: variant);
begin
  Value := HourOfTheYear(EncodeDateTime(2026, 1, 2, 5, 0, 0, 0)); // 29
end;

Usage​

HourOfTheYear returns the zero-based encoded hour index since 1 January at the start of the containing calendar year.

Parameters

NameTypeDescription
AValueTDateTime, constEncoded date/time whose day-of-year and hour fields are used.

Returns

HourOf(AValue) + (DayOfTheYear(AValue) - 1) * 24. A common year ranges from 0..8759; a leap year ranges from 0..8783.

Important usage notes

  • The index uses the calendar year, not the ISO week-numbering year.
  • Leap years contain 24 additional indexed hours after 29 February.
  • Minutes, seconds and milliseconds are discarded.
  • The value advances by 24 for every calendar day regardless of daylight-saving transitions, so it is not a timezone-aware elapsed-hour count.
  • The Word return type safely contains the maximum supported result.

Errors

Unsupported raw values can fail during date/time decoding. No function catches the exception.

Additional Technical Info​

HourOfTheYear returns a zero-based calendar index based on complete prior calendar days in the year and the current hour-of-day field.

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.HourOfTheYear. DayOfTheYear supplies the one-based calendar ordinal and HourOf supplies the current clock hour.

Side effects

None.

Performance and concurrency

Constant-time calendar extraction and arithmetic with no shared state.

Related entries

External references

Created 2026-07-15