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HourOfTheWeek

Function HourOfTheWeek(const AValue: TDateTime): Word

Example​

procedure ScriptEvent(var Value: variant);
begin
  // Wednesday at 05:00: two complete days plus five hours.
  Value := HourOfTheWeek(EncodeDateTime(2026, 7, 15, 5, 0, 0, 0)); // 53
end;

Usage​

HourOfTheWeek returns the zero-based encoded hour index since Monday at the start of the containing ISO week.

Parameters

NameTypeDescription
AValueTDateTime, constEncoded date/time whose ISO weekday and hour fields are used.

Returns

HourOf(AValue) + (DayOfTheWeek(AValue) - 1) * 24, in the range 0..167.

Important usage notes

  • Monday 00:00 begins at 0; Sunday 23:xx returns 167.
  • This is an encoded calendar index, not elapsed real-world hours. A daylight-saving transition does not make the week contain 167 or 169 indexed hours.
  • Minutes, seconds and milliseconds are discarded.
  • The week definition is fixed to ISO Monday-to-Sunday and is not locale-configurable.
  • No UTC/local conversion occurs.

Errors

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

Additional Technical Info​

HourOfTheWeek returns a zero-based index within an ISO Monday-to-Sunday week. It combines the Monday-based weekday number with the current hour 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.HourOfTheWeek. DayOfTheWeek supplies Monday 1 through Sunday 7; complete earlier weekdays contribute 24 hours each, then HourOf supplies the current hour.

Side effects

None.

Performance and concurrency

Constant-time field extraction and integer arithmetic with no shared state.

Related entries

External references

Created 2026-07-15