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RecodeMilliSecond

Function RecodeMilliSecond(const AValue: TDateTime; const AMilliSecond: Word): TDateTime

Example​

procedure ScriptEvent(var Value: variant);
var
  InputValue: TDateTime;
begin
  InputValue := EncodeDateTime(2026, 7, 18, 9, 30, 15, 250);
  Value := RecodeMilliSecond(InputValue, 500); // 09:30:15.500
end;

Usage​

RecodeMilliSecond replaces the millisecond field while preserving all other encoded components.

Parameters

NameTypeDescription
AValueTDateTime, constBase value whose other date/time fields are preserved.
AMilliSecondWord, constReplacement millisecond from 0 through 999, or 65535 to preserve the base millisecond.

Returns

A newly encoded TDateTime with the resolved millisecond field and every other decoded field preserved.

Behaviour

  • Zero clears the millisecond field; 999 sets its greatest valid value.
  • No carry or rounding is performed. A value above 999 is invalid rather than advancing the whole second.
  • The base is not modified, and all larger fields remain the same.
  • Valid pre-epoch values are recomposed with sign-aware encoding.

Important usage notes

  • 65535 preserves the field. The named Velox RecodeLeaveFieldAsIs constant is not exposed to scripts.
  • A manually calculated input with finer-than-millisecond precision is first decoded to a millisecond field, so even a sentinel/no-op call rebuilds at Velox's millisecond resolution.
  • The routine is field replacement, not an elapsed-millisecond adjustment. Use IncMilliSecond for arithmetic.
  • No timezone conversion occurs.

Usage notes

Use this routine when the surrounding second must remain fixed. It is not suitable for preserving precision finer than one millisecond.

Additional Technical Info​

RecodeMilliSecond replaces the millisecond-within-second field and preserves the date, hour, minute and whole-second fields.

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.RecodeMilliSecond. It calls the shared RecodeDateTime terminal with AMilliSecond and the leave-as-is sentinel for all other fields. The terminal decodes the base and validates/re-encodes the complete field set.

Side effects

None on success. The failure path can read global locale separators for its message.

Errors

A replacement outside 0-999 and not equal to 65535, or an unsuitable base value, raises EConvertError. Velox does not catch or translate it.

Performance and concurrency

Constant-time decoding and encoding with no external I/O. Concurrent locale mutation can affect only failure-message text.

Related entries

External references

Created 2026-07-15