FormatFloat possible improvement

[bytebites]

Code: Pascal  [Select][+][-]

1. Function FormatFloat(Const Format : String; Value : Extended; Const FormatSettings: TFormatSettings) : String;
2.  
3. Var
4.   buf : Array[0..1024] of Char;
5.   Len: Integer;
6.  
7. Begin
8.   Len:=FloatToTextFmt(PChar(@Buf[0]),Value,PChar(Format),FormatSettings);
9.   Buf[Len]:=#0;
10.   Result:=StrPas(Pchar(@Buf[0]));
11. End;
12.  

Currently FormatFloat function uses StrPas to create result, is it possible to use SetString instead since the length is known?

[ASerge]

I suggest making it more safe:

Code: Pascal  [Select][+][-]

1. function FormatFloat(const Format: string; Value: Extended; const FormatSettings: TFormatSettings): string;
2.  
3.   procedure FormatCommon(Buf: PChar);
4.   var
5.     Len: SizeInt;
6.   begin
7.     Len := FloatToTextFmt(@Buf[0], Value, PChar(Format), FormatSettings);
8.     SetString(Result, Buf, Len);
9.   end;
10.  
11.   procedure FormatDynamicBuf;
12.   var
13.     Buf: PChar;
14.   begin
15.     Buf := GetMem(Length(Format) + 100);
16.     try
17.       FormatCommon(Buf);
18.     finally
19.       FreeMem(Buf);
20.     end;
21.   end;
22.  
23. var
24.   Buf: array[Byte] of Char;
25. begin
26.   if Length(Format) < 100 then
27.     FormatCommon(Buf)
28.   else
29.     FormatDynamicBuf;
30. end;

A simple test where the original gives an AV:

Code: Pascal  [Select][+][-]

1. procedure TForm1.Button1Click(Sender: TObject);
2. var
3.   LongFormat: string;
4. begin
5.   Memo1.Text := FormatFloat('0000', 0.0, DefaultFormatSettings);
6.   LongFormat := StringOfChar('0', 2000);
7.   Memo1.Append(FormatFloat(LongFormat, 0.0, DefaultFormatSettings));
8. end;

[AlexTP]

@bytebites
I suggested the same in GitLab issue, without reading this topic.
https://gitlab.com/freepascal.org/fpc/source/-/issues/41181