delphi xe5 StrToFloat 失败将ThousandSeparator更改为 ','

Question

我在这里做错了什么？我只是想将格式化字符串转换为 double 型，并使用 TFormatSettings 作为参数传递给 StrToFloat。我收到以下异常:

  '3,332.1' is not a valid floating point value.  

千位分隔符和小数分隔符是 TFormatSettings 中的预期值(“,”和“.”)。

procedure TForm2.Button1Click(Sender: TObject);
var
  FS: TFormatSettings; 
  S: String;
  V: double;
begin
  FS:= TFormatSettings.Create; 
  codesite.Send('ThousandSeparator', FS.ThousandSeparator);  //correct ','
  codesite.Send('DecimalSeparator', FS.DecimalSeparator);    //correct '.'
  S := '3,332.1';
  try
    V := StrToFloat(S, FS);
  except on E: Exception do
    ShowMessage(e.Message);
  end;
  CodeSite.Send('S', S);
  CodeSite.Send('V', V);
end;

Answer 1

此行为是按照设计的。来自 documentation ，我强调的是:

Use StrToFloat to convert a string, S, to a floating-point value. S must consist of an optional sign (+ or -), a string of digits with an optional decimal point, and an optional mantissa. The mantissa consists of 'E' or 'e' followed by an optional sign (+ or -) and a whole number. Leading and trailing blanks are ignored.

The DecimalSeparator global variable or its TFormatSettings equivalent defines the character that is used as a decimal point. Thousand separators and currency symbols are not allowed in the string. If S does not contain a valid value, StrToFloat raises an EConvertError exception.

因此，将包含千位分隔符的字符串传递给此函数是错误的。