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DayOfWeek

function DayOfWeek(const DateTime: TDateTime): Word;

Example​

procedure ScriptEvent(var Value: variant);
begin
  Value := DayOfWeek(EncodeDate(2026, 7, 19)); // 1: Sunday
end;

Usage​

DayOfWeek returns the Velox weekday number for a TDateTime value, with Sunday 1 and Saturday 7.

Parameters

NameTypeDescription
DateTimeTDateTime, constDate/time whose calendar date is converted to a weekday.

Returns

1 Sunday, 2 Monday, 3 Tuesday, 4 Wednesday, 5 Thursday, 6 Friday or 7 Saturday.

Behaviour

The numbering is fixed by the function and does not follow a locale's configured first day of week. The time component is ignored.

Errors

Valid dates do not raise. The script binding adds no validation or exception handling.

Additional Technical Info​

DayOfWeek returns Delphi's traditional Sunday-first weekday number. Use it only when that convention is required; ISO-related DateUtils functions use a different Monday-first result.

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

Implementation

The modified PascalScript runtime registers this entry directly to Delphi 37.0 System.SysUtils.DayOfWeek. The RTL converts the value to TTimeStamp, then calculates TimeStamp.Date mod 7 + 1. Only the date field participates.

Edge cases and quirks

  • This function is not ISO 8601. DayOfTheWeek returns Monday 1 through Sunday 7 and should be used with ISO week functions.
  • The return type in Velox is Word; Free Pascal documents Integer, but the ordinary values are the same 1..7 range.
  • No timezone conversion occurs. The weekday comes from the date already encoded in the value.
  • Unsupported raw values outside the Delphi timestamp domain have no validated result contract.

Side effects

None.

Performance and concurrency

Constant-time timestamp/modulo operation with no allocation or shared state.

Related entries

  • DayOfTheWeek supplies Monday-first ISO numbering.
  • DecodeDate returns the calendar fields rather than weekday.

External references

Created 2026-07-15