IsValidDateTime

Function IsValidDateTime(const AYear, AMonth, ADay, AHour, AMinute, ASecond, AMilliSecond: Word): Boolean

Example

procedure ScriptEvent(var Value: variant);
begin
  Value := IsValidDateTime(2026, 7, 18, 24, 0, 0, 0); // True under DateUtils validation rules
end;

Usage

IsValidDateTime validates date and millisecond-resolution time fields using the DateUtils date and time rules.

Parameters

Name	Type	Description
AYear	Word, const	Gregorian year.
AMonth	Word, const	Month number.
ADay	Word, const	Day of month.
AHour	Word, const	Hour, including the exact 24:00 special case.
AMinute	Word, const	Minute.
ASecond	Word, const	Second.
AMilliSecond	Word, const	Millisecond.

Returns

True only when IsValidDate and IsValidTime both return True.

Behaviour

• Date fields use the supported Gregorian range and real month lengths.
• Ordinary time fields allow 00:00:00.000 through 23:59:59.999.
• The exact tuple 24:00:00.000 is also accepted by IsValidTime, so it is accepted here.

Important usage notes

• The exposed EncodeDateTime routine does not accept hour 24. Therefore True from this validator is not sufficient evidence that the same seven fields can be passed directly to that encoder. Normalise exact 24:00 to 00:00 on the next date before encoding.
• Leap seconds such as second 60 are rejected.
• The routine validates components only and attaches no timezone or offset.

Usage notes

Use the result as the documented field or date predicate only. It does not establish a timezone, business calendar or input provenance.

Additional Technical Info

IsValidDateTime validates date and millisecond-resolution time fields using the DateUtils date and time rules.

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

Implementation

The DateUtils import binds directly to Delphi 37.0 System.DateUtils.IsValidDateTime. It directly combines IsValidDate(AYear, AMonth, ADay) and IsValidTime(AHour, AMinute, ASecond, AMilliSecond) with Boolean and.

Side effects

None.

Errors

There is no wrapper exception handling. Ordinary out-of-range Word fields return False rather than raising.

Performance and concurrency

Constant-time field decoding or comparison with no external I/O. The routine uses no shared mutable state.

Related entries

• IsValidDate implements the date half of this result.
• IsValidTime implements the time half and documents 24:00.
• InvalidDateTimeError always raises the general conversion error.

External references

• Embarcadero System.DateUtils.IsValidDateTime
• Free Pascal IsValidDateTime

Created 2026-07-15