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SecondOfTheMonth

Function SecondOfTheMonth( const AValue : TDateTime) : LongWord

Example​

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

Usage​

SecondOfTheMonth returns the zero-based second index within the encoded calendar month.

Parameters

NameTypeDescription
AValueTDateTime, constDate/time whose calendar-month position is required.

Returns

An unsigned value from zero through 2,419,199, 2,505,599, 2,591,999 or 2,678,399 depending on whether the month contains 28, 29, 30 or 31 days.

Behaviour

  • The result resets at midnight on the first day of each month.
  • Leap-year rules alter February's maximum.
  • Milliseconds are ignored.
  • It is a field index, not elapsed time between independently tagged instants.

Errors

Decode exceptions propagate unchanged.

Usage notes

Use SecondsBetween when comparing two values rather than locating one value within a month.

Additional Technical Info​

SecondOfTheMonth returns the zero-based whole-second position within the encoded calendar month, starting at midnight on its first day.

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

Implementation

The DateUtils import calls System.DateUtils.SecondOfTheMonth. Delphi calculates SecondOf(AValue) + MinuteOfTheMonth(AValue) * 60; the delegated minute routine incorporates zero-based day and hour fields.

Edge cases and quirks

  • The returned LongWord matches Delphi's unsigned Cardinal.
  • Timezone/DST rules do not change the encoded index.
  • Invalid input can raise while decoding date/time fields.
  • Free Pascal provides a compatible same-name index routine.

Side effects

None.

Performance and concurrency

Constant-time field decoding and integer arithmetic with no I/O.

Related entries

External references

Created 2026-07-15