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SecondOfTheWeek

Function SecondOfTheWeek( const AValue : TDateTime) : LongWord

Example​

procedure ScriptEvent(var Value: variant);
var
  InputValue: TDateTime;
begin
  InputValue := EncodeDateTime(2026, 7, 7, 1, 2, 3, 900); // Tuesday
  Value := SecondOfTheWeek(InputValue); // 90123
end;

Usage​

SecondOfTheWeek returns the zero-based second index within the Monday-based ISO week.

Parameters

NameTypeDescription
AValueTDateTime, constValue whose position within its ISO week is required.

Returns

A LongWord from zero at Monday 00:00:00 through 604,799 at Sunday 23:59:59.

Behaviour

  • The result resets every Monday at encoded midnight.
  • Milliseconds are discarded.
  • ISO week-year ownership can differ from calendar-year ownership near New Year, but this index only needs the Monday-based weekday.
  • No timezone conversion occurs.

Errors

Core date/time conversion errors propagate.

Usage notes

Use StartOfTheWeek to obtain the encoded Monday boundary itself.

Additional Technical Info​

SecondOfTheWeek returns the zero-based whole-second position in the ISO week containing the value. ISO weeks begin on Monday.

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

Implementation

The DateUtils import binds to System.DateUtils.SecondOfTheWeek. It combines SecondOf with MinuteOfTheWeek * 60. The minute chain derives a Monday-one ISO weekday from Delphi's date/time timestamp.

Edge cases and quirks

  • The result is always based on seven encoded 86,400-second days, not real elapsed seconds through DST transitions.
  • Invalid values can raise in the decode/timestamp chain.
  • The unsigned return type fits the full weekly range.
  • Free Pascal documents the same Monday-based week model.

Side effects

None.

Performance and concurrency

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

Related entries

External references

Created 2026-07-15