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HourOf

Function HourOf(const AValue: TDateTime): Word

Example​

procedure ScriptEvent(var Value: variant);
begin
  Value := HourOf(EncodeTime(14, 30, 45, 0)); // 14
end;

Usage​

HourOf extracts the zero-based hour-of-day component from a TDateTime value.

Parameters

NameTypeDescription
AValueTDateTime, constEncoded date/time whose hour field is extracted.

Returns

A Word in 0..23. Midnight returns 0; values from 23:00 through 23:59:59.999 return 23.

Important usage notes

  • The function returns a component, not elapsed hours and not a 1-based clock value.
  • It performs no timezone conversion; the result is the hour already encoded in AValue.
  • The decode path handles valid negative pre-epoch TDateTime values according to Velox's special sign convention.
  • Sub-millisecond fractions do not change the hour except where timestamp rounding crosses an hour boundary.

Errors

Unsupported or non-finite raw values can fail during timestamp conversion. No function catches the exception.

Additional Technical Info​

HourOf returns the hour field encoded in a TDateTime, using 24-hour numbering from 0 through 23. The calendar date does not affect the result.

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.HourOf. The terminal calls DecodeTime, writes the hour into the function result and discards the decoded minute, second and millisecond fields. DecodeTime converts through Delphi's millisecond timestamp representation.

Side effects

None.

Performance and concurrency

Constant-time field extraction with no allocation or shared state.

Related entries

External references

Created 2026-07-15