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'ReadLn across lines'

Ron_de_Weijze
on
Medium Priority
383 Views
Last Modified: 2010-04-05
Hi,

My problem seems to be with ReadLn. The following is code I have not written (but did pay for). I cannot get it to work. It does work in a compiled version from many years ago.

A line (0ÿNew Noteÿÿÿ-1ÿ80ÿ50ÿ65535ÿ16ÿ0ÿ1ÿ10ÿaþ
bÿ-1) in a datafile is read using

procedure TNotePool.Load(FileName : string);
var
   DataFile : TextFile;
   Line     : string;
   Note     : TNote;
begin
   AssignFile(DataFile, FileName);
   Reset(DataFile);

   while not EOF(DataFile) do
   begin
      Readln(DataFile, Line);

      Note.ID           := StrToInt(GetFieldFromLine(Line));
      Note.Caption      := GetFieldFromLine(Line);
      Note.ImageFile     := GetFieldFromLine(Line);
      Note.IconFile      := GetFieldFromLine(Line);
      Note.NoteType     := StrToInt(GetFieldFromLine(Line));
      Note.Width        := StrToInt(GetFieldFromLine(Line));
      Note.Height       := StrToInt(GetFieldFromLine(Line));
      Note.Color        := StrToInt(GetFieldFromLine(Line));
      Note.IconSize     := StrToInt(GetFieldFromLine(Line));
      Note.IconLocation := StrToInt(GetFieldFromLine(Line));
      Note.Transparent  := Boolean(StrToInt(GetFieldFromLine(Line)));
      Note.TextSize     := StrToInt(GetFieldFromLine(Line));
      Note.Memo         := SetCRs(GetFieldFromLine(Line));  
          { ATTENTION : TEMPORARILY }
      Note.AggID        := StrToInt(Line);

      if OldLoad then
         AddItem(Note)
      else
         AddItemRaw(Note);
   end;

   CloseFile(DataFile);
end;

The line that is read is cut into a first part on line 1 of the datafile and a second part on line 2 of the datafile. The line that is read must be put into the note (Memo field) and it must be cut in half (continuing after the carriage return) on the memo. Now, the line-separator þ (#254) that is used is not recognized by the

function TPool.GetFieldFromLine(var Str : string) : string;
var
   Temp  : string;
begin
   Temp := Copy(Str, 1, Pos(#255, Str) - 1);
   System.Delete(Str, 1, Pos(#255, Str));

   Result := Temp;
end;

Therefore, the memo field remains empty and an exception is raised.

Strangely,

function TPool.SetCRs(Text : ansistring) : ansistring;
var
   i : longint;
   TempText : ansistring;
begin
   for i := 1 to Length(Text) do
   begin
      if Text[i] = #254 then
         TempText := TempText + #13
      else
         TempText := TempText + Text[i];
   end;

   Result := TempText;
end;

is supposed to work with the extracted memo-field, but, of course, if empty, it cannot.

Do you see how this is supposed to work? I will say this question is difficult, but I am clearly a beginner..

Thanks,

Ron dW
Comment
Watch Question

Commented:
The line shouldn't be cut in the datafile - the þ is used as a line separator, not a standard CR.

The code looks OK (though there's no error handling at all).

After the ReadLn( DataFile , Line)

see how long 'Line' is

i.e. Line.Length()

Author

Commented:
Thanks for your comment, Andrew.
I agree that the line shouldn't be cut in the datafile.
However, this seems to be the way that the datafile is written in..

procedure TNotePool.Save(FileName : string);
var
   DataFile   : TextFile;
   i          : integer;
begin
   AssignFile(DataFile, FileName);
   Rewrite(DataFile);    

   for i := 0 to Count - 1 do
   begin
      WriteLn(DataFile,
              i, #255,
              TNoteItem(Item[i]).Caption, #255,
              TNoteItem(Item[i]).ImageFile, #255,
              TNoteItem(Item[i]).IconFile, #255,
              TNoteItem(Item[i]).NoteType, #255,
              TNoteItem(Item[i]).Width, #255,
              TNoteItem(Item[i]).Height, #255,
              TNoteItem(Item[i]).Color, #255,
              TNoteItem(Item[i]).IconSize, #255,
              TNoteItem(Item[i]).IconLocation, #255,
              integer(TNoteItem(Item[i]).Transparent), #255,
              TNoteItem(Item[i]).TextSize, #255,
              KillCRs(TNoteItem(Item[i]).Memo), #255,
                   { ATTENTION : TEMPORARILY }
              m_SheetPool.m_ItemList.IndexOf(TNoteItem(Item[i]).
              AggItem)
             );
   end;

   CloseFile(DataFile);
end;

using..

function TPool.KillCRs(Text : ansistring) : ansistring;
var
   i : longint;
   TempText : ansistring;
begin
   for i := 1 to Length(Text) do
   begin
      if Text[i] = #13 then
         TempText := TempText + #254
      else
         TempText := TempText + Text[i];
   end;

   Result := TempText;
end;

Or would you say this code is nòt supposed to cut the line to be written in half after the þ line separator onto the datafile?

Thanks

Author

Commented:
BTW I wìll look into Line.Length() and let you know.

Commented:
Indeed - it should remove the CRs so the line isn't cut.

Perhaps there's a LF got into there somehow.
Perhaps it's not really cut and it's just how your viewing it..

Author

Commented:
Thanks, I'll investigate and let you know ASAP!
Top Expert 2004

Commented:
getting this result

0
New Note


-1
80
50
65535
16
0
1
10
aþb
-1

using this sample

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;

type
  TForm1 = class(TForm)
    Edit1: TEdit;
    Button1: TButton;
    Memo1: TMemo;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

function SplitStr(Var AString : String; ADelim : String) : String;
var APos : Integer;
begin
  Result := '';
  APos := Pos(ADelim,AString);
  if APos > 0 then
  begin
    Result := Copy(AString,1,APos-1);
    AString := copy(Astring,APos+length(Adelim),MaxLongInt);
  end
  else
  begin
    Result := AString;
    AString := '';
  end;
end;

procedure TForm1.Button1Click(Sender: TObject);
var s : string;
begin
  s := edit1.text;
  memo1.lines.clear;
  while s <> '' do
    memo1.lines.add(splitstr(s,#255));

end;

end.

meikl ;-)

Author

Commented:
Thanks Andrew and Meikl,

The line is *really* cut in the datafile, for this is true after looking at the line ("a" over "b" in a note) written by the compiled code and the current code using EditPad. The line produced by the current code can be read by the compiled code but it cannot be read by the current code.

Text and Length(Text) in TPool.KillCRs are:

     Text: 'a'#$D#$A'b'
     Length(Text): Inaccessible value

I do not see LF #10.

I wished I'd understand this, otherwise I might resort to code like Meikl's.

Thanks again.
Commented:
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Top Expert 2004
Commented:
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Author

Commented:
Thank you both!

I changed the

if Text[i] = #13

in KillCRs into

if Text[i] = #$A then
         TempText := TempText + #254
   else if Text[i] = #$D then
         TempText := TempText

Looks like a change in Delphi itself (I use version 7.0)?

Case closed (for now).

Hope you don't mind sharing the points! :)
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