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MinuteSpan

Function MinuteSpan(const ANow, AThen: TDateTime): Double

Example​

procedure ScriptEvent(var Value: variant);
var
  FirstValue, SecondValue: TDateTime;
begin
  FirstValue := EncodeDateTime(2026, 7, 18, 9, 0, 0, 0);
  SecondValue := EncodeDateTime(2026, 7, 18, 9, 1, 30, 0);
  Value := MinuteSpan(FirstValue, SecondValue); // approximately 1.5
end;

Usage​

MinuteSpan returns the absolute fractional-minute span from Velox's raw numeric TDateTime difference.

Parameters

NameTypeDescription
ANowTDateTime, constFirst raw encoded value. It need not be current or later.
AThenTDateTime, constSecond raw encoded value. Argument order does not affect the result.

Returns

The non-negative absolute raw day difference multiplied by 1,440 minutes per day, as a Double.

Behaviour

  • Reversing the arguments produces the same result.
  • Partial minutes are retained subject to binary floating-point precision.
  • No timezone or daylight-saving conversion occurs.
  • Ordinary post-epoch encoded values produce the expected raw span.

Important usage notes

  • Timed values before 30 December 1899 use Velox's negative fractional encoding. Raw subtraction can therefore return a materially incorrect chronological interval when a pre-epoch time is involved, especially across the epoch.
  • A mathematically exact decimal such as 1.5 minutes may be represented with a small floating-point error.
  • The absolute result discards direction.
  • Unlike MinutesBetween, this routine does not normalise or round inputs to timestamp milliseconds.

Usage notes

Prefer MinutesBetween for chronological complete-minute calculations and whenever pre-epoch dates may occur.

Additional Technical Info​

MinuteSpan returns the absolute raw numeric difference between two TDateTime values scaled to minutes. The Double result can retain fractional minutes, but the raw subtraction is not chronologically correct for timed values before Delphi's epoch.

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.MinuteSpan. Its shared helper compares and subtracts the raw floating-point values; the result is then multiplied by the fixed number of minutes per day. No timestamp conversion is performed.

Side effects

None.

Errors

There is no explicit validation. Non-finite raw values can propagate non-useful floating-point output.

Performance and concurrency

Constant-time floating-point arithmetic with no external I/O or shared mutable state.

Related entries

External references

Created 2026-07-15