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StrToFloat

function StrToFloat(const S: string): Extended;

Example​

procedure ScriptEvent(var Value: variant);
begin
  Value := StrToFloat('125');  // 125.0 in every decimal locale
end;

Usage​

StrToFloat converts system-locale numeric text to an Extended value and raises when parsing fails.

Parameters

NameTypeDescription
SstringSigned floating text. The decimal character must equal the Windows system locale's decimal separator; an E/e exponent can include its own sign.

Returns

The parsed Extended value. Precision and range follow the Velox target's definition of Extended; on targets where Extended aliases Double, it does not provide 80-bit precision.

Behaviour

The accepted ordinary form is an optional sign, digits with an optional locale decimal separator, and an optional E/e exponent. Leading and trailing ASCII spaces are ignored. Thousands separators and currency symbols are not accepted.

Errors

Invalid syntax, a disallowed separator or out-of-range input raises EConvertError, which propagates into the script. Use StrToFloatDef when a fallback is intentional.

Usage notes

For machine-to-machine data, normalise the source format deliberately before this call or use a conversion whose separator contract is fixed. Do not assume a workstation's displayed regional format matches a Velox Service host.

Additional Technical Info​

StrToFloat converts numeric text to Extended using a fresh snapshot of the Windows system locale. It supports ordinary decimal and scientific notation, propagating a conversion exception when the whole value is not valid for the selected locale.

The example deliberately avoids a decimal separator. It is source-reviewed and is not executed by the documentation workflow.

Implementation

Velox deliberately replaces PascalScript's built-in StrToFloat registration with vxStrToFloat. The wrapper calls TFormatSettings.Create(LOCALE_SYSTEM_DEFAULT) for each invocation and passes that local record to Delphi System.SysUtils.StrToFloat(S, AFormatSettings). The Delphi terminal parses the complete string through its text-to-floating implementation.

Edge cases and quirks

  • Locale comes from Windows LOCALE_SYSTEM_DEFAULT, not the Velox service account's user locale and not Delphi's mutable global FormatSettings. A script can therefore behave differently on hosts with different system regional settings.
  • A dot is not universally valid. If the system decimal separator is a comma, 1.5 fails and 1,5 is the applicable form.
  • The installed Delphi 37.0 terminal additionally recognises case-insensitive NAN, INF, +INF and -INF, although the concise public routine description focuses on ordinary numeric grammar.
  • An exponent marker must be followed by exponent digits. The entire remaining input must be consumed apart from accepted surrounding spaces.
  • Overflow, invalid floating operations or an exponent outside the target range fail conversion rather than returning a saturated value.
  • Free Pascal documents a similar format-settings overload, but its version history and supported floating representation are compatibility information only; Velox executes Delphi's implementation.

Side effects

None outside constructing a local format-settings record and allocating temporary conversion state.

Performance and concurrency

Parsing is linear in input length. Creating locale settings on every call adds an operating-system locale lookup but avoids dependence on Delphi's mutable global format record. The local settings overload is safe from concurrent changes to that Delphi global; a host system-locale change can still affect later calls.

Related entries

  • StrToFloatDef returns a supplied value when parsing fails.
  • StrToBool tries Delphi's global-format floating parser as its first Boolean rule and therefore has a different locale source.
  • FloatToStr formats a floating value using the same Velox system-locale policy.

External references

Created 2026-07-15