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In Delphi1, using FloatToStrF or CurrToStrF will automatically use the DecimalSeparator character to represent a decimal mark. Unfortunately DecimalSeparator is declared in SysUtils as Char1,2:

var 
  DecimalSeparator: Char;

While the LOCALE_SDECIMAL is allowed to be up to three characters:

Character(s) used for the decimal separator, for example, "." in "3.14" or "," in "3,14". The maximum number of characters allowed for this string is four, including a terminating null character.

This causes Delphi to fail to read the decimal separator correctly; falling back to assume a default decimal separator of ".":

DecimalSeparator := GetLocaleChar(DefaultLCID, LOCALE_SDECIMAL, '.');

On my computer, which is quite a character, this cause floating point and currency values to be incorrectly localized with a U+002E (full stop) decimal mark.

i am willing to call the Windows API functions directly, which are designed to convert floating point, or currency, values into a localized string:

Except these functions take a string of picture codes, where the only characters allowed are:

  • Characters "0" through "9" (U+0030..U+0039)
  • One decimal point (.) if the number is a floating-point value (U+002E)
  • A minus sign in the first character position if the number is a negative value (U+002D)

What would be a good way1 to convert a floating point, or currency, value to a string that obeys those rules? e.g.

  • 1234567.893332
  • -1234567

given that the local user's locale (i.e. my computer):

A horrible, horrible, hack, which i could use:

function FloatToLocaleIndependantString(const v: Extended): string;
var
   oldDecimalSeparator: Char;
begin
   oldDecimalSeparator := SysUtils.DecimalSeparator;
   SysUtils.DecimalSeparator := '.'; //Windows formatting functions assume single decimal point
   try
      Result := FloatToStrF(Value, ffFixed, 
            18, //Precision: "should be 18 or less for values of type Extended"
            9 //Scale 0..18.   Sure...9 digits before decimal mark, 9 digits after. Why not
      );
   finally
      SysUtils.DecimalSeparator := oldDecimalSeparator;
   end;
end;

Additional info on the chain of functions the VCL uses:

Note

1 in my version of Delphi
2 and in current versions of Delphi

4

2 回答 2

2

Delphi 确实提供了一个称为FloatToDecimal将浮点（例如Extended）和Currency值转换为有用结构以进行进一步格式化的过程。例如：

FloatToDecimal(..., 1234567890.1234, ...);

给你：

TFloatRec
   Digits: array[0..20] of Char = "12345678901234"
   Exponent: SmallInt =           10
   IsNegative: Boolean =          True

whereExponent给出小数点左边的位数。

有一些特殊情况需要处理：

  • 指数为零

       Digits: array[0..20] of Char = "12345678901234"
   Exponent: SmallInt =           0
   IsNegative: Boolean =          True

    表示小数点左边没有数字，例如.12345678901234

  • 指数为负

       Digits: array[0..20] of Char = "12345678901234"
   Exponent: SmallInt =           -3
   IsNegative: Boolean =          True

    意味着您必须在小数点和第一位数字之间放置零，例如.00012345678901234

  • 指数是-32768（NaN，不是数字）

       Digits: array[0..20] of Char = ""
   Exponent: SmallInt =           -32768
   IsNegative: Boolean =          False

    表示该值不是数字，例如NAN

  • 指数是32767（INF或-INF）

       Digits: array[0..20] of Char = ""
   Exponent: SmallInt =           32767
   IsNegative: Boolean =          False

    表示该值是正无穷大或负无穷大（取决于IsNegative值），例如-INF

我们可以FloatToDecimal以此为起点创建一个独立于语言环境的“图片代码”字符串。

然后可以将此字符串传递给适当的 WindowsGetNumberFormat或GetCurrencyFormat函数以执行实际正确的本地化。

我编写了自己的CurrToDecimalString并将FloatToDecimalString数字转换为所需的区域独立格式：

class function TGlobalization.CurrToDecimalString(const Value: Currency): string;
var
    digits: string;
    s: string;
    floatRec: TFloatRec;
begin
    FloatToDecimal({var}floatRec, Value, fvCurrency, 0{ignored for currency types}, 9999);

    //convert the array of char into an easy to access string
    digits := PChar(Addr(floatRec.Digits[0]));

    if floatRec.Exponent > 0 then
    begin
        //Check for positive or negative infinity (exponent = 32767)
        if floatRec.Exponent = 32767 then //David Heffernan says that currency can never be infinity. Even though i can't test it, i can at least try to handle it
        begin
            if floatRec.Negative = False then
                Result := 'INF'
            else
                Result := '-INF';
            Exit;
        end;

        {
            digits:    1234567 89
              exponent--------^ 7=7 digits on left of decimal mark
        }
        s := Copy(digits, 1, floatRec.Exponent);

        {
            for the value 10000:
                digits:   "1"
                exponent: 5
            Add enough zero's to digits to pad it out to exponent digits
        }
        if Length(s) < floatRec.Exponent then
            s := s+StringOfChar('0', floatRec.Exponent-Length(s));

        if Length(digits) > floatRec.Exponent then
            s := s+'.'+Copy(digits, floatRec.Exponent+1, 20);
    end
    else if floatRec.Exponent < 0 then
    begin
        //check for NaN (Exponent = -32768)
        if floatRec.Exponent = -32768 then  //David Heffernan says that currency can never be NotANumber. Even though i can't test it, i can at least try to handle it
        begin
            Result := 'NAN';
            Exit;
        end;

        {
            digits:   .000123456789
                         ^---------exponent
        }

        //Add zero, or more, "0"'s to the left
        s := '0.'+StringOfChar('0', -floatRec.Exponent)+digits;
    end
    else
    begin
        {
            Exponent is zero.

            digits:     .123456789
                            ^
        }
        if length(digits) > 0 then
            s := '0.'+digits
        else
            s := '0';
    end;

    if floatRec.Negative then
        s := '-'+s;

    Result := s;
end;

除了 ,和的边缘情况NAN，我现在可以将这些字符串传递给 Windows：INF-INF

class function TGlobalization.GetCurrencyFormat(const DecimalString: WideString; const Locale: LCID): WideString;
var
    cch: Integer;
    ValueStr: WideString;
begin
    Locale
        LOCALE_INVARIANT
        LOCALE_USER_DEFAULT     <--- use this one (windows.pas)
        LOCALE_SYSTEM_DEFAULT
        LOCALE_CUSTOM_DEFAULT       (Vista and later)
        LOCALE_CUSTOM_UI_DEFAULT    (Vista and later)
        LOCALE_CUSTOM_UNSPECIFIED   (Vista and later)
}

    cch := Windows.GetCurrencyFormatW(Locale, 0, PWideChar(DecimalString), nil, nil, 0);
    if cch = 0 then
        RaiseLastWin32Error;

    SetLength(ValueStr, cch);
    cch := Windows.GetCurrencyFormatW(Locale, 0, PWideChar(DecimalString), nil, PWideChar(ValueStr), Length(ValueStr));
    if (cch = 0) then
        RaiseLastWin32Error;

    SetLength(ValueStr, cch-1); //they include the null terminator  /facepalm
    Result := ValueStr;
end;

和实现留给读者作为练习FloatToDecimalString（GetNumberFormat因为我实际上还没有写浮点数，只是货币 - 我不知道我将如何处理指数符号）。

还有鲍勃的叔叔；Delphi 下正确本地化的浮点数和货币。

我已经完成了正确本地化整数、日期、时间和日期时间的工作。

注意：任何代码都会发布到公共领域。无需归属。

于 2011-08-17T21:46:33.320 回答
2

好的，这可能不是您想要的，但它适用于 D2007 及更高版本。线程安全和所有。

uses Windows,SysUtils;

var
  myGlobalFormatSettings : TFormatSettings;

// Initialize special format settings record
GetLocaleFormatSettings( 0,myGlobalFormatSettings);
myGlobalFormatSettings.DecimalSeparator := '.';


function FloatToLocaleIndependantString(const value: Extended): string;
begin
  Result := FloatToStrF(Value, ffFixed, 
        18, //Precision: "should be 18 or less for values of type Extended"
        9, //Scale 0..18.   Sure...9 digits before decimal mark, 9 digits after. Why not
        myGlobalFormatSettings
  );
end;
于 2011-08-16T22:24:55.183 回答