FloatToStr when decimal separator is not a dot

[lainz]

Hi, for example when the system locale is Spanish we use comma as decimal separator "," instead of dot "." that causes a problem when using FloatToStr and StrToFloat.

[skrzacikus]

@lainz use DefaultFormatSettings.DecimalSeparator := ','

[lainz]

That's not a solution. The solution must be in JsonTools. We already patched it, so it always uses dot instead of comma. But I'm reporting so others doesn't have the same issue.

Our patch is like this:

function StrToFloatDecDef(s: string; rDefault: real):Double;
var sTemp:string;
begin
   sTemp:=StringReplace(s,'.',DecimalSeparator,[rfReplaceAll]);
   result:=StrToFloatDef(sTemp, rDefault);
end;


function FloattoStrDec(aValor: Real): String;
var
  sTmp: string;
begin
    sTmp := FormatFloat('0.0000',aValor);
    sTmp := StringReplace(sTmp, ThousandSeparator, '', [rfReplaceAll, rfIgnoreCase]);
    Result := StringReplace(sTmp, DecimalSeparator, '.',[rfReplaceAll, rfIgnoreCase]);
end;  

procedure TJsonNode.SetAsNumber(Value: Double);
begin
  if FParent = nil then
    Error(SRootNodeKind);
  if FKind <> nkNumber then
  begin
    Clear;
    FKind := nkNumber;
  end;
  FValue := FloattoStrDec(Value);
end;   

function TJsonNode.Add(const Name: string; const N: Double): TJsonNode; overload;
begin
  Result := Add(nkNumber, Name, FloattoStrDec(N));
end;   

function TJsonNode.GetAsNumber: Double;
begin
  if FParent = nil then
    Error(SRootNodeKind);
  if FKind <> nkNumber then
  begin
    Clear;
    FKind := nkNumber;
    FValue := '0';
    Exit(0);
  end;
  Result := StrToFloatDecDef(FValue, 0);
end;  

[hafedh-trimeche]

Using TFormatSettings would be the solution:

procedure TJsonDataHelper.SetFloat(const Path:string;const AValue:Extended);
var
  FormatSettings : TFormatSettings;
  JsonData       : TJsonData;
begin
  Lock;
  JsonData := PathToObject(Path,nkNumber);
  if Assigned(JsonData) then
  begin
    {$IFDEF DCC}
    FormatSettings := TFormatSettings.Create;
    {$ENDIF}
    FormatSettings.DecimalSeparator := '.';
    try
      JsonData.Value := FormatFloat('0.0'+StringOfChar('#',30),AValue,FormatSettings);
    except
      JsonData.AsNull;
    end;
  end;
  Unlock;
end;

[JacoFourie]

@lainz I have the same issue. I found I had to change the locale of the machine to have a . as a decimal place.
Do you have a pas file with your path applied?

[JacoFourie]

OK I added it myself and all is working. Thanks for this.

[lainz]

You're welcome. I don't share my unit since I think I modified a bit more, and it requires some of the project files, so I can't share.

[dalfy15]

Привет, например, если в системе используется испанский язык, мы используем запятую в качестве десятичного разделителя «,» вместо точки «.», что вызывает проблемы при использовании функций FloatToStr и StrToFloat.

just do it this way:

function NextToken(var C: PChar; out T: TJsonToken): Boolean;
...
if C^ in ['-', '0'..'9'] then
begin
if C^ = '-' then
Inc(C);
if C^ in ['0'..'9'] then
begin
while C^ in ['0'..'9'] do
Inc(C);
if C^ in ['.', ','] then // <--- replace it with this!
begin
if C^ <> DefaultFormatSettings.DecimalSeparator then // <--- add this!
C^ := DefaultFormatSettings.DecimalSeparator; // <--- add this!
Inc(C);
...