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FloatToStr

function FloatToStr(Value: Extended): string;

Example​

procedure ScriptEvent(var Value: variant);
begin
  Value := FloatToStr(1234.5);
  // The decimal separator follows the Windows system-default locale.
end;

Usage​

FloatToStr formats an Extended value using Velox's system-default locale format settings.

Parameters

NameTypeDescription
ValueExtendedFloating-point value to format. Precision of Extended depends on the deployed Velox target.

Returns

General-format text using up to 15 significant digits and the decimal separator from TFormatSettings.Create(LOCALE_SYSTEM_DEFAULT). Velox selects fixed or scientific notation according to the value. Thousands separators are not inserted.

Special values return NAN, INF or -INF.

Errors

Locale-initialisation and string-allocation failures propagate. NaN and infinities are formatted tokens rather than errors.

Usage notes

For machine interchange, explicitly normalise the decimal separator and define accepted exponent/precision rules, or use a purpose-built fixed contract. Do not parse this output under an unrelated locale without supplying matching rules.

Additional Technical Info​

FloatToStr formats an Extended floating-point value in Delphi general-number format with 15 significant digits. Velox deliberately supplies a fresh Windows system-default locale settings record; it does not call Delphi's parameterless overload.

The example does not assert exact punctuation because its result is locale-dependent. It is source-reviewed and is not executed by the documentation workflow.

Implementation

The formats import registers the script name FloatToStr against the Velox function vxFloatToStr. That wrapper creates a local TFormatSettings snapshot for LOCALE_SYSTEM_DEFAULT and calls System.SysUtils.FloatToStr(Value, FormatSettings). The selected RTL overload delegates to general floating-point text conversion with 15 significant digits.

Edge cases and quirks

  • Output can use a decimal comma or another locale-specific decimal separator. Do not assume a period.
  • Large or small magnitudes can use exponent notation. The exact changeover is part of Delphi's general-format algorithm, not a Velox configuration option.
  • Formatting is limited to 15 significant digits even where Win32 Extended holds more precision. It is not a lossless serialisation of every Extended value.
  • On current Win32 Delphi targets, Extended normally uses 80-bit precision; on Win64 it aliases Double. Calculations and rounded text near precision boundaries can differ between deployments.
  • The locale is the Windows system default, which can differ from the interactive user's locale and from Delphi's global FormatSettings. A Velox service therefore need not format identically to a desktop test under another system configuration.

Side effects

No intended external side effect. The call reads operating-system locale data into a local settings record.

Performance and concurrency

Each call constructs locale settings and allocates a result string. Because the formatting overload receives a local settings value, it does not depend on concurrent changes to Delphi's global FormatSettings; a change to the operating-system default between calls can still change later results.

External references

Created 2026-07-15